#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
using ll = long long;
#define N 800010

const int mod = 998244353;
int n;
vector<pair<int, bool>>e[N];
int dp[N][3];
bool b[N];
vector<vector<int>>a;
vector<int>A, B, r;
int limit = 1, l = 0;
string s;
int ksm(int a, int b)
{
    int ans = 1;
    while (b) {if (b & 1) ans = 1LL * ans * a % mod; b >>= 1; a = 1LL * a * a % mod;}
    return ans;
}
void FFT(vector<int>&a, int type)
{
    for (int i = 0; i < limit; i ++) if (i < r[i]) swap(a[i], a[r[i]]);
    for (int mid = 1; mid < limit; mid <<= 1)
    {
        int Wn = ksm(3, (mod - 1) / (mid << 1));
        if (type == -1) Wn = ksm(Wn, mod - 2);
        for (int j = 0, R = (mid << 1); j < limit; j += R)
        {
            for (int k = 0, w = 1; k < mid; k ++, w = 1LL * w * Wn % mod)
            {
                int x = a[j + k], y = 1LL * a[j + k + mid] * w % mod;
                a[j + k] = (x + y) % mod;
                a[j + k + mid] = (x + mod - y) % mod;
            }
        }
 
    }      
     if (type == -1)
        {
            int inv = ksm(limit, mod - 2);
            for (int i = 0; i < limit; i ++) a[i] = 1LL * a[i] * inv % mod;
        }
}
vector<int> operator *(const vector<int>&a, const vector<int>&b)
{
    int n = a.size(), m = b.size();
    limit = 1, l = 0;
    while (limit <= n + m) limit <<= 1, l ++;
    A.assign(limit, 0); B.assign(limit, 0); r.assign(limit, 0);
    for (int i = 0; i < limit; i ++)r[i] = (r[i >> 1] >> 1) | ((i & 1) << (l - 1));
    for (int i = 0; i < n; i ++) A[i] = a[i];
    for (int i = 0; i < m; i ++) B[i] = b[i];
    // cout << "GG:" << endl;
    // for (int i = 0; i < n; i ++)
    // {
    //     cout << A[i] << ' ';
    // }
    // cout << endl;
    // for (int i = 0; i < m; i ++)
    // {
    //     cout << B[i] << ' ';
    // }
    // cout << endl;
    FFT(A, 1); FFT(B, 1);
    // for (int i = 0; i < n; i ++) cout << A[i] << ' '; cout << endl;
    // FFT(A, -1); FFT(B, -1);
    // for (int i = 0; i < n; i ++) cout << A[i] << ' '; cout << endl;
    for (int i = 0; i < limit; i ++) A[i] = 1LL * A[i] * B[i] % mod;
    FFT(A, -1);
    vector<int>c = A;
    // for (int i = 0; i < limit; i ++) cout << A[i] << ' ';
    // cout << endl;
    while (!c.back()) c.pop_back();
    return c;
}
vector<int> sol(int l, int r)
{
    if (l == r) {return a[l];}
    int mid = (l + r) >> 1;
    return sol(l, mid) * sol(mid + 1, r);
}
void dfs(int u, int fa)
{

    int son = 0;
    for (auto [v, t] : e[u]) if (v != fa)
    {
        dfs(v, u);
    }    
    dp[u][1] = 1; 
    if (b[u] == 0) dp[u][0] = 1;
    if (b[u] == 1) dp[u][2] = 1;
    a.clear();
    a = {{dp[u][0], dp[u][1], dp[u][2]}};
    for (auto [v, t] : e[u]) if (v != fa)
    {
        vector<int> tmp;
        if (t == 0)tmp = {dp[v][0], dp[v][1], 0};
        if (t == 1)tmp = {0, dp[v][1], dp[v][2]};
        a.push_back(tmp); son ++;
    }
    int m = a.size();
    vector<int>ans = sol(0, m - 1);
    dp[u][0] = ans[son];
    dp[u][1] = ans[son + 1];
    dp[u][2] = ans[son + 2];
    // cout << "?:" << u << endl;
    // cout << dp[u][0] << ' ' << dp[u][1] << ' ' << dp[u][2] << endl;
}
void solve(void)
{
    cin >> n >> s;
    // mt19937 rnd(time(0));
    for (int i = 1; i <= n; i ++)b[i] = (s[i - 1] == 'S');
    for (int i = 1; i < n; i ++)
    {
        int u, v;
        cin >> u >> v;
        e[u].push_back({v, 0});
        e[v].push_back({u, 1});
    }
    dfs(1, 0);
    cout << dp[1][1] << '\n';
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int T = 1;
    for (int i = 1; i <= T; i++)
    solve();

    return 0;
}