#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;
    }
  }
}


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



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 = brute::run();
    printf("%u\n", ans.x);
    
#ifdef LOCAL
const Mint brt=brute::run();
cerr<<"brt = "<<brt<<endl;
#endif
  }
#ifndef LOCAL
  break;
#endif
  }
  return 0;
}