#include <bits/stdc++.h>
using namespace std;
const long long MOD = 998244353;
const long long HALF = 499122177;
const std::vector<long long> ntt_root = {1, 998244352, 911660635, 372528824, 929031873, 452798380, 922799308, 781712469, 476477967, 166035806, 258648936, 584193783, 63912897, 350007156, 666702199, 968855178, 629671588, 24514907, 996173970, 363395222, 565042129, 733596141, 267099868, 15311432};
const std::vector<long long> ntt_iroot = {1, 998244352, 86583718, 509520358, 337190230, 87557064, 609441965, 135236158, 304459705, 685443576, 381598368, 335559352, 129292727, 358024708, 814576206, 708402881, 283043518, 3707709, 121392023, 704923114, 950391366, 428961804, 382752275, 469870224};
void ntt(std::vector<long long> &A){
  int N = A.size();
  int M = __builtin_ctz(N);
  for (int i = M - 1; i >= 0; i--){
    for (int j = 0; j < N; j += (2 << i)){
      long long z = 1;
      for (int k = 0; k < (1 << i); k++){
        long long a = A[j + k] + A[j + (1 << i) + k];
        if (a >= MOD){
          a -= MOD;
        }
        long long b = A[j + k] - A[j + (1 << i) + k];
        if (b < 0){
          b += MOD;
        }
        b *= z;
        b %= MOD;
        A[j + k] = a;
        A[j + (1 << i) + k] = b;
        z *= ntt_root[i + 1];
        z %= MOD;
      }
    }
  }
}
void ntt_inv(std::vector<long long> &A){
  int N = A.size();
  int M = __builtin_ctz(N);
  for (int i = 0; i < M; i++){
    for (int j = 0; j < N; j += (2 << i)){
      long long z = 1;
      for (int k = 0; k < (1 << i); k++){
        A[j + (1 << i) + k] *= z;
        A[j + (1 << i) + k] %= MOD;
        long long a = A[j + k] + A[j + (1 << i) + k];
        if (a >= MOD){
          a -= MOD;
        }
        long long b = A[j + k] - A[j + (1 << i) + k];
        if (b < 0){
          b += MOD;
        }
        A[j + k] = a;
        A[j + (1 << i) + k] = b;
        z *= ntt_iroot[i + 1];
        z %= MOD;
      }
    }
  }
  long long Ninv = 1;
  for (int i = 0; i < M; i++){
    Ninv *= HALF;
    Ninv %= MOD;
  }
  for (int i = 0; i < N; i++){
    A[i] *= Ninv;
    A[i] %= MOD;
  }
}
std::vector<long long> convolution(std::vector<long long> A, std::vector<long long> B){
  int sz = A.size() + B.size() - 1;
  int N = sz == 1 ? 1 : 1 << (32 - __builtin_clz(sz - 1));
  A.resize(N);
  B.resize(N);
  ntt(A);
  ntt(B);
  std::vector<long long> ans(N);
  for (int i = 0; i < N; i++){
    ans[i] = A[i] * B[i] % MOD;
  }
  ntt_inv(ans);
  ans.resize(sz);
  return ans;
}
int main(){
  int n;
  cin >> n;
  string S;
  cin >> S;
  vector<vector<pair<int, int>>> E(n);
  for (int i = 0; i < n - 1; i++){
    int u, v;
    cin >> u >> v;
    u--;
    v--;
    E[u].push_back(make_pair(v, 0));
    E[v].push_back(make_pair(u, 1));
  }
  vector<int> p(n, -1);
  vector<int> d(n);
  vector<vector<int>> c(n);
  vector<int> b;
  queue<int> Q;
  Q.push(0);
  while (!Q.empty()){
    int v = Q.front();
    Q.pop();
    b.push_back(v);
    for (auto P : E[v]){
      int w = P.first;
      if (w != p[v]){
        p[w] = v;
        if (P.second == 0){
          d[w] = 0;
        } else {
          d[w] = -1;
        }
        c[v].push_back(w);
        Q.push(w);
      }
    }
  }
  vector<int> dp(n, 0);
  for (int i = 0; i < n; i++){
    if (S[i] == 'S'){
      dp[i] = 1;
    }
  }
  reverse(b.begin(), b.end());
  for (int v : b){
    if (v != 0){
      dp[p[v]] += dp[v];
    }
  }
  for (int i = 0; i < n; i++){
    dp[i] += d[i];
  }
  vector<vector<long long>> dp2(n, vector<long long>(2, 0));
  for (int v : b){
    int cnt = c[v].size();
    int s = 0;
    vector<vector<long long>> f(cnt + 1);
    for (int j = 0; j < cnt; j++){
      s += dp[c[v][j]];
      f[j] = dp2[c[v][j]];
    }
    f[cnt] = {1, 1};
    auto dfs = [&](auto dfs, int L, int R) -> vector<long long> {
      if (R - L == 1){
        return f[L];
      } else {
        int m = (L + R) / 2;
        return convolution(dfs(dfs, L, m), dfs(dfs, m, R));
      }
    };
    vector<long long> P = dfs(dfs, 0, cnt + 1);
    if (0 <= dp[v] - s && dp[v] - s < P.size()){
      dp2[v][0] = P[dp[v] - s];
    }
    if (0 <= dp[v] + 1 - s && dp[v] + 1 - s < P.size()){
      dp2[v][1] = P[dp[v] + 1 - s];
    }
  }
  cout << dp2[0][0] << endl;
}