#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")

using namespace std;

const int N = 2e5 + 5, P = 998244353;

string s;
vector< pair<int, int> > G[N];
int f[3][N];
mt19937 rnd;

void dfs(int x, int fa = -1, int c = 1) {
    shuffle(G[x].begin(), G[x].end(), rnd);
    vector<int> tf(2000); tf[1000] = 1; if (s[x] == 'F') tf[1001] = 1; else tf[999] = 1;
    for (auto [v, w] : G[x]) if (v != fa) {
        dfs(v, x, w);
        vector<int> tg(2000);
        for (int i = 0; i < 2000; ++i) {
            tg[i] = 1ll * tf[i] * f[1][v] % P;
        }
        if (w == 2) {
            for (int i = 0; i < 1999; ++i) {
                tg[i + 1] = (tg[i + 1] + 1ll * tf[i] * f[2][v]) % P;
            }
        } else {
            for (int i = 1; i < 2000; ++i) {
                tg[i - 1] = (tg[i - 1] + 1ll * tf[i] * f[0][v]) % P;
            }
        }
        tf = tg;
    }
    for (int i = 0; i <= 2; ++i) if (i == 1 || i == c) {
        f[i][x] = tf[999 + i];
    }
}

signed main() {
    int n; scanf("%d", &n); cin >> s; s = ' ' + s;
    for (int i = 1; i < n; ++i) {
        int x, y; scanf("%d%d", &x, &y);
        G[x].push_back(make_pair(y, 2));
        G[y].push_back(make_pair(x, 0));
    }
    dfs(1);
    printf("%d\n", f[1][1]);
    return 0;
}