#include <bits/stdc++.h>
#define debug(x) cout << #x << " :==  " << x << endl
#define FINISH cout << "FINISH" << endl;
#define el '\n'
using namespace std;
using ll = long long;
const int inf = 1000000000;
const int mod = 998244353;
ll up(ll x)
{
	return (x % mod + mod) % mod;
}
void solve()
{
	int n;
	cin >> n;
	string s;
	cin >> s;
	s = " " + s;
	vector<vector<int>> edge1(n + 1), edge(n + 1);
	vector<int> siz(n + 1, 0);
	vector<int> col(n + 1);
	for (int i = 1; i < n; i++) {
		int x, y;
		cin >> x >> y;
		edge1[x].push_back(y);
	}
	auto bfs = [&](int st) {
		int cnt = 0;
		queue<int> q;
		q.push(st);
		// cout << "START " << st << endl;
		while (!q.empty()) {
			int x = q.front();
			// cout << x << " ";
			q.pop();
			cnt++;
			if (col[x]) {
				edge[st].push_back(col[x]);
				edge[col[x]].push_back(st);
			}
			else
				col[x] = st;
			if (s[x] == 'S' && x != st) {
				continue;
			}
			for (auto to : edge1[x]) {
				q.push(to);
			}
		}
		/*cout << endl;
		FINISH*/
		return cnt;
	};
	for (int i = 1; i <= n; i++) {
		if (s[i] == 'S') {
			siz[i] = bfs(i);
		}
	}
	/*for (int i = 1; i <= n; i++) {
		for (auto j : edge[i]) {
			cout << "edge " << i << " " << j << endl;
		}
	}
	FINISH*/
	vector<int> vis(n + 1, 0);
	vector<array<ll, 2>> dp(n + 1);
	vector<int> res;
	function<void(int, int)> dfs = [&](int x, int fa) {
		vis[x] = 1;
		dp[x][0] = siz[x] - 1;
		dp[x][1] = 1;
		for (auto to : edge[x]) {
			if (to == fa)
				continue;
			dfs(to, x);
			dp[x][1] = dp[to][0] * dp[x][1] % mod + dp[x][0] * dp[to][1] % mod;
			dp[x][0] = dp[to][0] * dp[x][0] % mod;
		}
	};
	for (int i = 1; i <= n; i++) {
		if (s[i] == 'S' && !vis[i]) {
			dfs(i, i);
			res.push_back(i);
		}
	}
	ll ans = 1;
	for (int i = 0; i < res.size(); i++) {
		ans = ans * (dp[res[i]][0] + dp[res[i]][1]) % mod;
	}
	cout << up(ans) << el;
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	int T = 1;
	// cin >> T;
	while (T--) {
		solve();
	}
	return 0;
}