#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }
#define COLOR(s) ("\x1b[" s "m")

////////////////////////////////////////////////////////////////////////////////
template <unsigned M_> struct ModInt {
  static constexpr unsigned M = M_;
  unsigned x;
  constexpr ModInt() : x(0U) {}
  constexpr ModInt(unsigned x_) : x(x_ % M) {}
  constexpr ModInt(unsigned long long x_) : x(x_ % M) {}
  constexpr ModInt(int x_) : x(((x_ %= static_cast<int>(M)) < 0) ? (x_ + static_cast<int>(M)) : x_) {}
  constexpr ModInt(long long x_) : x(((x_ %= static_cast<long long>(M)) < 0) ? (x_ + static_cast<long long>(M)) : x_) {}
  ModInt &operator+=(const ModInt &a) { x = ((x += a.x) >= M) ? (x - M) : x; return *this; }
  ModInt &operator-=(const ModInt &a) { x = ((x -= a.x) >= M) ? (x + M) : x; return *this; }
  ModInt &operator*=(const ModInt &a) { x = (static_cast<unsigned long long>(x) * a.x) % M; return *this; }
  ModInt &operator/=(const ModInt &a) { return (*this *= a.inv()); }
  ModInt pow(long long e) const {
    if (e < 0) return inv().pow(-e);
    ModInt a = *this, b = 1U; for (; e; e >>= 1) { if (e & 1) b *= a; a *= a; } return b;
  }
  ModInt inv() const {
    unsigned a = M, b = x; int y = 0, z = 1;
    for (; b; ) { const unsigned q = a / b; const unsigned c = a - q * b; a = b; b = c; const int w = y - static_cast<int>(q) * z; y = z; z = w; }
    assert(a == 1U); return ModInt(y);
  }
  ModInt operator+() const { return *this; }
  ModInt operator-() const { ModInt a; a.x = x ? (M - x) : 0U; return a; }
  ModInt operator+(const ModInt &a) const { return (ModInt(*this) += a); }
  ModInt operator-(const ModInt &a) const { return (ModInt(*this) -= a); }
  ModInt operator*(const ModInt &a) const { return (ModInt(*this) *= a); }
  ModInt operator/(const ModInt &a) const { return (ModInt(*this) /= a); }
  template <class T> friend ModInt operator+(T a, const ModInt &b) { return (ModInt(a) += b); }
  template <class T> friend ModInt operator-(T a, const ModInt &b) { return (ModInt(a) -= b); }
  template <class T> friend ModInt operator*(T a, const ModInt &b) { return (ModInt(a) *= b); }
  template <class T> friend ModInt operator/(T a, const ModInt &b) { return (ModInt(a) /= b); }
  explicit operator bool() const { return x; }
  bool operator==(const ModInt &a) const { return (x == a.x); }
  bool operator!=(const ModInt &a) const { return (x != a.x); }
  friend std::ostream &operator<<(std::ostream &os, const ModInt &a) { return os << a.x; }
};
////////////////////////////////////////////////////////////////////////////////

constexpr unsigned MO = 998244353;
using Mint = ModInt<MO>;

constexpr int LIM_INV = 800'010;
Mint inv[LIM_INV], fac[LIM_INV], invFac[LIM_INV];

void prepare() {
  inv[1] = 1;
  for (int i = 2; i < LIM_INV; ++i) {
    inv[i] = -((Mint::M / i) * inv[Mint::M % i]);
  }
  fac[0] = invFac[0] = 1;
  for (int i = 1; i < LIM_INV; ++i) {
    fac[i] = fac[i - 1] * i;
    invFac[i] = invFac[i - 1] * inv[i];
  }
}
Mint binom(Int n, Int k) {
  if (n < 0) {
    if (k >= 0) {
      return ((k & 1) ? -1 : +1) * binom(-n + k - 1, k);
    } else if (n - k >= 0) {
      return (((n - k) & 1) ? -1 : +1) * binom(-k - 1, n - k);
    } else {
      return 0;
    }
  } else {
    if (0 <= k && k <= n) {
      assert(n < LIM_INV);
      return fac[n] * invFac[k] * invFac[n - k];
    } else {
      return 0;
    }
  }
}


// Meldable
// 0 for null, ts[0] = T()
// chPoint(u, a): point update
// chRange(u, a, b): range update s.t. T() -> T()
//   T::push(T *l, T *r)
//   T::pull(const T &l, const T &r)
//   T::meld(const T &t)
template <class T> struct Seg {
  static constexpr int NUM_NODES = 1 << 23;
  int l0, r0;
  int nodesLen;
  int ls[NUM_NODES], rs[NUM_NODES];
  T ts[NUM_NODES];
  void init(int l0_, int r0_) {
    l0 = l0_;
    r0 = r0_;
    nodesLen = 1;
    ls[0] = rs[0] = 0;
    ts[0] = T();
  }
  int newNode() {
    assert(nodesLen < NUM_NODES);
    const int u = nodesLen++;
    ls[u] = rs[u] = 0;
    ts[u] = T();
    return u;
  }
  void push(int u) {
    ts[u].push(ls[u] ? &ts[ls[u]] : nullptr, rs[u] ? &ts[rs[u]] : nullptr);
  }
  void pull(int u) {
    ts[u].pull(ts[ls[u]], ts[rs[u]]);
  }

  template <class F, class... Args>
  void chPoint(int &u, int l, int r, int a, F f, Args &&... args) {
    if (!u) u = newNode();
    if (l + 1 == r) {
      (ts[u].*f)(args...);
      return;
    }
    const int mid = l + ((r - l) >> 1);
    push(u);
    (a < mid)
      ? chPoint(ls[u], l, mid, a, f, args...)
      : chPoint(rs[u], mid, r, a, f, args...);
    pull(u);
  }
  template <class F, class... Args>
  void chPoint(int &u, int a, F f, Args &&... args) {
    assert(l0 <= a); assert(a < r0);
    chPoint(u, l0, r0, a, f, args...);
  }

  template <class F, class... Args>
  void chRange(int &u, int l, int r, int a, int b, F f, Args &&... args) {
    if (!u) return;
    if (b <= l || r <= a) return;
    if (a <= l && r <= b) {
      (ts[u].*f)(args...);
      return;
    }
    const int mid = l + ((r - l) >> 1);
    push(u);
    chRange(ls[u], l, mid, a, b, f, args...);
    chRange(rs[u], mid, r, a, b, f, args...);
    pull(u);
  }
  template <class F, class... Args>
  void chRange(int &u, int a, int b, F f, Args &&... args) {
    assert(l0 <= a); assert(a <= b); assert(b <= r0);
    chRange(u, l0, r0, a, b, f, args...);
  }

  T get(int u, int l, int r, int a, int b) {
    if (!u) return T();
    if (b <= l || r <= a) return T();
    if (a <= l && r <= b) return ts[u];
    const int mid = l + ((r - l) >> 1);
    push(u);
    const T tL = get(ls[u], l, mid, a, b);
    const T tR = get(rs[u], mid, r, a, b);
    pull(u);
    T t;
    t.pull(tL, tR);
    return t;
  }
  T get(int u, int a, int b) {
    assert(l0 <= a); assert(a <= b); assert(b <= r0);
    return get(u, l0, r0, a, b);
  }

  // Frees v.
  int meld(int u, int v, int l, int r) {
    if (!u) return v;
    if (!v) return u;
    if (l + 1 == r) {
      ts[u].meld(ts[v]);
      return u;
    }
    const int mid = l + ((r - l) >> 1);
    push(u);
    push(v);
    ls[u] = meld(ls[u], ls[v], l, mid);
    rs[u] = meld(rs[u], rs[v], mid, r);
    pull(u);
    return u;
  }
  int meld(int u, int v) {
    return meld(u, v, l0, r0);
  }

  void print(int depth, int u, int l, int r) const {
    if (!u) return;
    cerr << string(2 * depth, ' ') << u << " [" << l << ", " << r << ") " << ts[u] << endl;
    if (l + 1 == r) return;
    const int mid = l + ((r - l) >> 1);
    print(depth + 1, ls[u], l, mid);
    print(depth + 1, rs[u], mid, r);
  }
  void print(int u) const {
    if (!u) cerr << "[Seg::print] null" << endl;
    print(0, u, l0, r0);
  }
};


int N, R;
vector<int> C;
vector<int> A, B;

vector<pair<Int, int>> cus;
vector<int> ids;
vector<vector<int>> graph;


namespace brute {
vector<int> mns;
void dfs(int u, int p) {
  mns[u] = ids[u];
  for (const int v : graph[u]) if (p != v) {
    dfs(v, u);
    chmin(mns[u], mns[v]);
  }
}
Mint ans;
map<int, Mint> solve(int u, int p) {
  vector<pair<int, int>> xvs;
  for (const int v : graph[u]) if (p != v) {
    xvs.emplace_back(mns[v], v);
  }
  sort(xvs.begin(), xvs.end());
  const int len = xvs.size();
  map<int, Mint> tmp;
  for (int j = 0; j < len; ++j) {
    const int v = xvs[j].second;
    const auto res = solve(v, u);
    for (const auto &kv : res) {
      assert(xvs[j].first <= kv.first);
      int k;
      for (k = 0; k < len && xvs[k].first <= kv.first; ++k) if (j != k) {
        tmp[xvs[k].first] += ((k < j) ? (inv[k + 1] * inv[k + 2]) : (inv[k] * inv[k + 1])) * kv.second;
      }
      tmp[kv.first] += inv[k] * kv.second;
    }
  }
  map<int, Mint> ret;
  ret[ids[u]] += 1;
  for (const auto &kv : tmp) {
    ret[min(ids[u], kv.first)] += kv.second;
  }
  for (const auto &kv : ret) {
    ans += kv.second * cus[kv.first].first;
  }
/*
cerr<<"u = "<<u<<": xvs = "<<xvs<<endl;
cerr<<"u = "<<u<<": tmp = ";pv(tmp.begin(),tmp.end());
cerr<<"u = "<<u<<": ret = ";pv(ret.begin(),ret.end());
*/
  return ret;
}
Mint run() {
  mns.assign(N, -1);
  dfs(R, -1);
  ans = 0;
  solve(R, -1);
  return ans;
}
}  // brute


/*
  range sum -> add to somewhere
    to x[0]
              x[0] x[1] x[2] x[3]
      f[0] xxxx|----|----|----|----
      f[1] xxxx|xxxx|@@@@|@@@@|@@@@ 1/2
      f[2] xxxx|xxxx|xxxx|@@@@|@@@@ 1/2
      f[3] xxxx|xxxx|xxxx|xxxx|@@@@ 1/2
    to x[1]
              x[0] x[1] x[2] x[3]
      f[0] xxxx|----|oooo|oooo|oooo 1/2
      f[1] xxxx|xxxx|----|----|----
      f[2] xxxx|xxxx|xxxx|@@@@|@@@@ 1/6
      f[3] xxxx|xxxx|xxxx|xxxx|@@@@ 1/6
    to x[2]
              x[0] x[1] x[2] x[3]
      f[0] xxxx|----|----|oooo|oooo 1/6
      f[1] xxxx|xxxx|----|oooo|oooo 1/6
      f[2] xxxx|xxxx|xxxx|----|----
      f[3] xxxx|xxxx|xxxx|xxxx|@@@@ 1/12
    to x[3]
              x[0] x[1] x[2] x[3]
      f[0] xxxx|----|----|----|oooo 1/12
      f[1] xxxx|xxxx|----|----|oooo 1/12
      f[2] xxxx|xxxx|xxxx|----|oooo 1/12
      f[3] xxxx|xxxx|xxxx|xxxx|----
  
  range mul
       x[0] x[1] x[2] x[3]
    ----|----|----|----|----
         1/1  1/2  1/3  1/4
*/
namespace slow {
vector<int> mns;
void dfs(int u, int p) {
  mns[u] = ids[u];
  for (const int v : graph[u]) if (p != v) {
    dfs(v, u);
    chmin(mns[u], mns[v]);
  }
}
Mint ans;
map<int, Mint> solve(int u, int p) {
  vector<pair<int, int>> xvs;
  for (const int v : graph[u]) if (p != v) {
    xvs.emplace_back(mns[v], v);
  }
  sort(xvs.begin(), xvs.end());
  const int len = xvs.size();
  map<int, Mint> sum;
  vector<Mint> fs(len, 0);
  for (int j = 0; j < len; ++j) {
    if (j) {
      // range sum
      for (const auto &kv : sum) if (xvs[j].first <= kv.first) {
        fs[j] += kv.second;
      }
    }
    const int v = xvs[j].second;
    const auto res = solve(v, u);
    // meld
    for (const auto &kv : res) {
      sum[kv.first] += kv.second;
    }
  }
  map<int, Mint> tmp;
  for (int j = 0; j < len; ++j) {
    if (j > 0) {
      tmp[xvs[j].first] += (inv[j] * inv[j + 1]) * fs[j];
    }
    if (j < len - 1) {
      // range sum
      Mint all = 0;
      for (const auto &kv : sum) if (xvs[j + 1].first <= kv.first) {
        all += kv.second;
      }
      tmp[xvs[j].first] += (inv[j + 1] * inv[j + 2]) * (all - fs[j + 1]);
    }
  }
  // range mul
  for (int j = 0; j < len; ++j) {
    for (const auto &kv : sum) if (xvs[j].first <= kv.first && (j + 1 == len || kv.first < xvs[j + 1].first)) {
      tmp[kv.first] += inv[j + 1] * kv.second;
    }
  }
  
  // attach u
  map<int, Mint> ret;
  ret[ids[u]] += 1;
  for (const auto &kv : tmp) {
    ret[min(ids[u], kv.first)] += kv.second;
  }
  for (const auto &kv : ret) {
    ans += kv.second * cus[kv.first].first;
  }
/*
cerr<<"u = "<<u<<": xvs = "<<xvs<<endl;
cerr<<"u = "<<u<<": tmp = ";pv(tmp.begin(),tmp.end());
cerr<<"u = "<<u<<": ret = ";pv(ret.begin(),ret.end());
*/
  return ret;
}
Mint run() {
  mns.assign(N, -1);
  dfs(R, -1);
  ans = 0;
  solve(R, -1);
  return ans;
}
}  // slow


namespace fast {
struct Node {
  Mint wt, sum, sum1;
  Mint lz;
  Node() : wt(0), sum(0), sum1(0), lz(1) {}
  friend ostream &operator<<(ostream &os, const Node &t) {
    return os << "(wt=" << t.wt << ", sum=" << t.sum << ", sum1=" << t.sum1 << ", lz=" << t.lz << ")";
  }
  void push(Node *l, Node *r) {
    if (lz != 1) {
      if (l) l->mul(lz);
      if (r) r->mul(lz);
      lz = 1;
    }
  }
  void pull(const Node &l, const Node &r) {
    sum = l.sum + r.sum;
    sum1 = l.sum1 + r.sum1;
  }
  void meld(const Node &t) {
    assert(wt == t.wt);
    sum += t.sum;
    sum1 += t.sum;
  }
  void mul(Mint val) {
    sum *= val;
    sum1 *= val;
    lz *= val;
  }
  // leaf
  void addToLeaf(Mint wt_, Mint val) {
    wt = wt_;
    sum += val;
    sum1 += wt * val;
  }
};

Seg<Node> seg;

void pointAdd(int &node, int x, Mint val) {
// cerr<<COLOR("93")<<"[pointAdd] "<<node<<" "<<x<<" "<<val<<COLOR()<<endl;
  if (val) {
    seg.chPoint(node, x, &Node::addToLeaf, cus[x].first, val);
  }
}

vector<int> mns;
void dfs(int u, int p) {
  mns[u] = ids[u];
  for (const int v : graph[u]) if (p != v) {
    dfs(v, u);
    chmin(mns[u], mns[v]);
  }
}
Mint ans;
int solve(int u, int p) {
  vector<pair<int, int>> xvs;
  for (const int v : graph[u]) if (p != v) {
    xvs.emplace_back(mns[v], v);
  }
  sort(xvs.begin(), xvs.end());
  const int len = xvs.size();
  int sum = 0;
  vector<Mint> fs(len, 0);
  for (int j = 0; j < len; ++j) {
    if (j) {
      fs[j] = seg.get(sum, xvs[j].first, N).sum;
    }
    const int v = xvs[j].second;
    const int res = solve(v, u);
    sum = seg.meld(sum, res);
  }
  vector<Mint> alls(len, 0);
  for (int j = 1; j < len; ++j) {
    alls[j] = seg.get(sum, xvs[j].first, N).sum;
  }
  int tmp = sum;
  for (int j = 0; j < len; ++j) {
    seg.chRange(tmp, xvs[j].first, (j + 1 == len) ? N : xvs[j + 1].first, &Node::mul, inv[j + 1]);
  }
  for (int j = 0; j < len; ++j) {
    Mint val = 0;
    if (j > 0) {
      val += (inv[j] * inv[j + 1]) * fs[j];
    }
    if (j < len - 1) {
      val += (inv[j + 1] * inv[j + 2]) * (alls[j + 1] - fs[j + 1]);
    }
    pointAdd(tmp, xvs[j].first, val);
  }
  
  // attach u
  int ret = tmp;
  {
    const Mint val = seg.get(ret, ids[u], N).sum;
    seg.chRange(ret, ids[u], N, &Node::mul, 0);
    pointAdd(ret, ids[u], val);
  }
  pointAdd(ret, ids[u], 1);
  ans += seg.ts[ret].sum1;
// cerr<<COLOR("91")<<"u = "<<u<<": xvs = "<<xvs<<COLOR()<<endl;
// seg.print(ret);
  return ret;
}
Mint run() {
  mns.assign(N, -1);
  dfs(R, -1);
  ans = 0;
  seg.init(0, N);
  solve(R, -1);
  return ans;
}
}  // fast


int main() {
  prepare();
  
  for (int numCases; ~scanf("%d", &numCases); ) { for (int caseId = 1; caseId <= numCases; ++caseId) {
    scanf("%d%d", &N, &R);
    --R;
    C.resize(N);
    for (int u = 0; u < N; ++u) {
      scanf("%d", &C[u]);
    }
    A.resize(N - 1);
    B.resize(N - 1);
    for (int i = 0; i < N - 1; ++i) {
      scanf("%d%d", &A[i], &B[i]);
      --A[i];
      --B[i];
    }
    
    cus.resize(N);
    for (int u = 0; u < N; ++u) {
      cus[u] = make_pair(C[u], u);
    }
    sort(cus.begin(), cus.end());
    ids.assign(N, -1);
    for (int x = 0; x < N; ++x) {
      ids[cus[x].second] = x;
    }
// cerr<<"cus = "<<cus<<endl;
    
    graph.assign(N, {});
    for (int i = 0; i < N - 1; ++i) {
      graph[A[i]].push_back(B[i]);
      graph[B[i]].push_back(A[i]);
    }
    
    const Mint ans = fast::run();
    printf("%u\n", ans.x);
    
#ifdef LOCAL
const Mint brt=brute::run();
cerr<<"brt = "<<brt<<endl;
#endif
  }
#ifndef LOCAL
  break;
#endif
  }
  return 0;
}