#ifdef LOCAL
#define _GLIBCXX_DEBUG 1
#define dbg(...) cerr << "LINE(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif

#if 0
    #include <ext/pb_ds/assoc_container.hpp>
    #include <ext/pb_ds/tree_policy.hpp>
 
    template<class T>
    using ordered_set = __gnu_pbds::tree<T, __gnu_pbds::null_type, std::less<T>, __gnu_pbds::rb_tree_tag,
        __gnu_pbds::tree_order_statistics_node_update>;
#endif

#include <vector> 
#include <list> 
#include <map> 
#include <set> 
#include <queue>
#include <stack> 
#include <bitset> 
#include <algorithm> 
#include <numeric> 
#include <utility> 
#include <sstream> 
#include <iostream> 
#include <iomanip> 
#include <cstdio> 
#include <cmath> 
#include <cstdlib> 
#include <ctime> 
#include <cstring>
#include <random>
#include <chrono>
#include <cassert>

using namespace std;
 
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define REP(i,n) for(int (i)=0;(i)<(int)(n);(i)++)

#define each(a,x) for (auto& a: x)
#define tcT template<class T
#define tcTU tcT, class U
#define tcTUU tcT, class ...U
template<class T> using V = vector<T>; 
template<class T, size_t SZ> using AR = array<T,SZ>;

typedef string str;
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
 
template<typename T, typename U> T &ctmax(T &x, const U &y){ return x = max<T>(x, y); }
template<typename T, typename U> T &ctmin(T &x, const U &y){ return x = min<T>(x, y); }
 
mt19937 rng((unsigned)chrono::steady_clock::now().time_since_epoch().count());
 
#define ts to_string
str ts(char c) { return str(1,c); }
str ts(bool b) { return b ? "true" : "false"; }
str ts(const char* s) { return (str)s; }
str ts(str s) { return s; }
str ts(vector<bool> v) { str res = "{"; F0R(i,sz(v)) res += char('0'+v[i]);	res += "}"; return res; }
template<size_t SZ> str ts(bitset<SZ> b) { str res = ""; F0R(i,SZ) res += char('0'+b[i]); return res; }
template<class A, class B> str ts(pair<A,B> p);
template<class T> str ts(T v) { bool fst = 1; str res = "{"; for (const auto& x: v) {if (!fst) res += ", ";	fst = 0; res += ts(x);}	res += "}"; return res;}
template<class A, class B> str ts(pair<A,B> p) {return "("+ts(p.first)+", "+ts(p.second)+")"; }
 
template<class A> void pr(A x) { cout << ts(x); }
template<class H, class... T> void pr(const H& h, const T&... t) { pr(h); pr(t...); }
void ps() { pr("\n"); }
template<class H, class... T> void ps(const H& h, const T&... t) { pr(h); if (sizeof...(t)) pr(" "); ps(t...); }
 
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) {cerr << ts(h); if (sizeof...(t)) cerr << ", ";	DBG(t...); }

tcTU> void re(pair<T,U>& p);
tcT> void re(V<T>& v);
tcT, size_t SZ> void re(AR<T,SZ>& a);

tcT> void re(T& x) { cin >> x; }
void re(double& d) { str t; re(t); d = stod(t); }
void re(long double& d) { str t; re(t); d = stold(t); }
tcTUU> void re(T& t, U&... u) { re(t); re(u...); }

tcTU> void re(pair<T,U>& p) { re(p.first,p.second); }
tcT> void re(V<T>& x) { each(a,x) re(a); }
tcT, size_t SZ> void re(AR<T,SZ>& x) { each(a,x) re(a); }
tcT> void rv(int n, V<T>& x) { x.rsz(n); re(x); }

constexpr bool multitest() {return 0;}
void solve();
int main() {
	ios_base::sync_with_stdio(false); cin.tie(NULL);
	int t = 1;
	if (multitest()) cin >> t;
	for (; t; t--) solve();
}












const ll mod = (119 << 23) + 1, root = 62; // = 998244353

ll modpow(ll b, ll e) {
	ll ans = 1;
	for (; e; b = b * b % mod, e /= 2)
		if (e & 1) ans = ans * b % mod;
	return ans;
}

typedef vector<ll> vl;
void ntt(vl &a) {
	int n = sz(a), L = 31 - __builtin_clz(n);
	static vl rt(2, 1);
	for (static int k = 2, s = 2; k < n; k *= 2, s++) {
		rt.resize(n);
		ll z[] = {1, modpow(root, mod >> s)};
		rep(i,k,2*k) rt[i] = rt[i / 2] * z[i & 1] % mod;
	}
	vi rev(n);
	rep(i,0,n) rev[i] = (rev[i / 2] | (i & 1) << L) / 2;
	rep(i,0,n) if (i < rev[i]) swap(a[i], a[rev[i]]);
	for (int k = 1; k < n; k *= 2)
		for (int i = 0; i < n; i += 2 * k) rep(j,0,k) {
			ll z = rt[j + k] * a[i + j + k] % mod, &ai = a[i + j];
			a[i + j + k] = ai - z + (z > ai ? mod : 0);
			ai += (ai + z >= mod ? z - mod : z);
		}
}
vl conv(const vl &a, const vl &b) {
	if (a.empty() || b.empty()) return {};
	int s = sz(a) + sz(b) - 1, B = 32 - __builtin_clz(s),
	    n = 1 << B;
	int inv = modpow(n, mod - 2);
	vl L(a), R(b), out(n);
	L.resize(n), R.resize(n);
	ntt(L), ntt(R);
	rep(i,0,n)
		out[-i & (n - 1)] = (ll)L[i] * R[i] % mod * inv % mod;
	ntt(out);
	return {out.begin(), out.begin() + s};
}

vector< vector<pii> > g;
string s;

vl getp(const vector<vl>& v, int l, int r) {
	if (l == r) return vl{1};
	if (l+1 == r) return v[l];

	int m = (l+r)/2;
	vl lt = getp(v, l, m);
	vl rt = getp(v, m, r);

	return conv(lt, rt);
}

pii go(int v, int p) {
	int dp = -1;

	vector< vl > ps;

	for (auto [x, d] : g[v]) {
		if (x == p) dp = d;
		else {
			pii xx = go(x, v);
			if (d == 1) ps.push_back(vl{0, xx.first, xx.second});
			else ps.push_back(vl{xx.second, xx.first});
		}
	}

	vl cv = getp(ps, 0, sz(ps));

	pii ans = {0, 0};

	ans.first = cv[sz(ps)];
	int idx = sz(ps) + (s[v]=='S' ? 1 : -1);
	if (idx >= 0 && idx < sz(cv)) ans.first = (ans.first + cv[idx]) % mod;
	
	idx = sz(ps)-dp;
	if (idx >= 0 && idx < sz(cv)) ans.second += cv[idx];
	idx = sz(ps) + (s[v]=='S' ? 1 : -1) - dp;
	if (idx >= 0 && idx < sz(cv)) ans.second = (ans.second + cv[ idx ]) % mod;

	return ans;
}







void solve() {
	int n; re(n);
	re(s);

	g= vector< vector<pii> >(n);
	for (int i = 0; i < n-1; i++) {
		int u, v; re(u, v); u--; v--;
		g[u].push_back({v, 1});
		g[v].push_back({u, -1});
	}

	ps( go(0, -1).first );
}