#include <bits/stdc++.h>

using namespace std;

using ll = long long;
#define int ll
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
using pii = pair<int, int>;
using vi = vector<int>;
#define fi first
#define se second
#define pb push_back

const int mod = 998244353;
const int N = 2e5+100;

typedef complex<double> C;
typedef vector<double> vd;
void fft(vector<C>& a) {
	int n = sz(a), L = 31 - __builtin_clz(n);
	static vector<complex<long double>> R(2, 1);
	static vector<C> rt(2, 1);  // (^ 10% faster if double)
	for (static int k = 2; k < n; k *= 2) {
		R.resize(n); rt.resize(n);
		auto x = polar(1.0L, acos(-1.0L) / k);
		rep(i,k,2*k) rt[i] = R[i] = i&1 ? R[i/2] * x : R[i/2];
	}
	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) {
			// C z = rt[j+k] * a[i+j+k]; // (25% faster if hand-rolled)  /// include-line
			auto x = (double *)&rt[j+k], y = (double *)&a[i+j+k];        /// exclude-line
			C z(x[0]*y[0] - x[1]*y[1], x[0]*y[1] + x[1]*y[0]);           /// exclude-line
			a[i + j + k] = a[i + j] - z;
			a[i + j] += z;
		}
}
vd conv(const vd& a, const vd& b) {
	if (a.empty() || b.empty()) return {};
	vd res(sz(a) + sz(b) - 1);
	int L = 32 - __builtin_clz(sz(res)), n = 1 << L;
	vector<C> in(n), out(n);
	copy(all(a), begin(in));
	rep(i,0,sz(b)) in[i].imag(b[i]);
	fft(in);
	for (C& x : in) x *= x;
	rep(i,0,n) out[i] = in[-i & (n - 1)] - conj(in[i]);
	fft(out);
	rep(i,0,sz(res)) res[i] = imag(out[i]) / (4 * n);
	return res;
}
typedef vector<ll> vl;
template<int M> vl convMod(const vl &a, const vl &b) {
	if (a.empty() || b.empty()) return {};
	vl res(sz(a) + sz(b) - 1);
	int B=32-__builtin_clz(sz(res)), n=1<<B, cut=int(sqrt(M));
	vector<C> L(n), R(n), outs(n), outl(n);
	rep(i,0,sz(a)) L[i] = C((int)a[i] / cut, (int)a[i] % cut);
	rep(i,0,sz(b)) R[i] = C((int)b[i] / cut, (int)b[i] % cut);
	fft(L), fft(R);
	rep(i,0,n) {
		int j = -i & (n - 1);
		outl[j] = (L[i] + conj(L[j])) * R[i] / (2.0 * n);
		outs[j] = (L[i] - conj(L[j])) * R[i] / (2.0 * n) / 1i;
	}
	fft(outl), fft(outs);
	rep(i,0,sz(res)) {
		ll av = ll(real(outl[i])+.5), cv = ll(imag(outs[i])+.5);
		ll bv = ll(imag(outl[i])+.5) + ll(real(outs[i])+.5);
		res[i] = ((av % M * cut + bv) % M * cut + cv) % M;
	}
	return res;
}
vector<int> conv(const vector<pair<int, int> >& v, int l, int r)
{
    if (l==r) return {1};
    if (l+1 == r)
        return {v[l].fi, v[l].se};
    int m = (l+r)/2;
    auto v1 = conv(v, l, m);
    auto v2 = conv(v, m, r);
    return convMod<mod>(v1, v2);
}

vector<pair<int, int> > g[N];
int dp[N][4]; // -1, 0, 1, 2
int b0[N];
int n;

void dfs(int v, int p)
{
    vector<pair<int, int> > abx;

    int s = b0[v];
    for (auto [i, d] : g[v])
        if (i!=p)
        {
            dfs(i, v);
            if (d == 0) // activation leads to s--, i++
            {
                s--;
                abx.pb({dp[i][0] + dp[i][1], dp[i][1] + dp[i][2]});
            }
            else
            {
                // s++, i--
                abx.pb({dp[i][1] + dp[i][2], dp[i][2] + dp[i][3]});
            }
        }
    for (auto& [x, y] : abx) x%=mod, y%=mod;
    vector<int> cm = conv(abx, 0, abx.size());

//    cout<<v<<" "<<p<<" "<<s<<" : ";
//    for (int i : cm) cout<<i<<" ";
//    cout<<"\n";

    for (int i=-1; i<=2; i++)
        if (i-s>=0 && i-s<cm.size())
            dp[v][i+1] = cm[i-s];
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin>>n;
    string s;
    cin>>s;
    for (int i=0; i<n; i++)
        b0[i+1] = (s[i] == 'F');
    for (int i=1; i<n; i++)
    {
        int x, y;
        cin>>x>>y;
        g[x].pb({y, 1});
        g[y].pb({x, 0});
    }
//
//    n = 200000;
//
//    for (int i=1; i<=n; i++)
//        b0[i] = rand()%2;
//    for (int i=2; i<=n; i++)
//    {
//        int q = rand()%2;
//        g[1].pb({i, q}), g[i].pb({1, 1-q});
//    }

    dfs(1, -1);
//    for (int i=1; i<=n; i++, cout<<"\n")
//    {
//        cout<<i<<" : ";
//        for (int j=0; j<4; j++)
//            cout<<dp[i][j]<<" ";
//    }
    cout<<(dp[1][1] + dp[1][2])%mod<<"\n";
}