#include <string.h>
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;

using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
template <typename T> using vc = vector<T>;
template <typename T> using vvc = vector<vector<T>>;
template <typename T> using vvvc = vector<vector<vector<T>>>;
template<class T> using pq = priority_queue<T,vector<T>,greater<T>>;
template <class T, class S> inline bool chmax(T &a, const S &b) { return (a < b ? a = b, 1 : 0); }
template <class T, class S> inline bool chmin(T &a, const S &b) { return (a > b ? a = b, 1 : 0); }

int dx4[] = {1,0,-1,0};
int dy4[] = {0,1,0,-1};

#define overload5(a, b, c, d, e, name, ...) name
#define overload4(a, b, c, d, name, ...) name
#define REP0(n) for(ll jidlsjf = 0; jidlsjf < n; ++jidlsjf)
#define REP1(i, n) for(ll i = 0; i < (n); ++i)
#define REP2(i, a, b) for(ll i = (a); i < (b); ++i)
#define REP3(i, a, b, c) for(ll i = (a); i < (b); i += (c))
#define rep(...) overload4(__VA_ARGS__, REP3, REP2, REP1, REP0)(__VA_ARGS__)
#define per0(n) for(int jidlsjf = 0; jidlsjf < (n); ++jidlsjf)
#define per1(i, n) for(ll i = (n)-1; i >= 0; --i)
#define per2(i, a, b) for(ll i = (a)-1; i >= b; --i)
#define per3(i, a, b, c) for(ll i = (a)-1; i >= (b); i -= (c))
#define per(...) overload4(__VA_ARGS__, per3, per2, per1, per0)(__VA_ARGS__)
#define setbits(j, n) for(ll iiiii = (n), j = lowbit(iiiii); iiiii; iiiii ^= 1 << j, j = lowbit(iiiii))
#define perm(v) for(bool permrepflag = true; (permrepflag ? exchange(permrepflag, false) : next_permutation(all(v)));)
#define fi first
#define se second
#define pb push_back
#define ppb pop_back
#define ppf pop_front
#define drop(s) cout << #s << endl, exit(0)
#define si(c) (int)(c).size()
#define lb(c, x) distance((c).begin(), lower_bound(all(c), (x)))
#define lbg(c, x) distance((c).begin(), lower_bound(all(c), (x), greater{}))
#define ub(c, x) distance((c).begin(), upper_bound(all(c), (x)))
#define ubg(c, x) distance((c).begin(), upper_bound(all(c), (x), greater{}))
#define rng(v, l, r) v.begin() + (l), v.begin() + (r)
#define all(c) c.begin(), c.end()
#define rall(c) c.rbegin(), c.rend()
#define SORT(v) sort(all(v))
#define REV(v) reverse(all(v))
#define UNIQUE(x) SORT(x), x.erase(unique(all(x)), x.end())
#define MIN(v) *min_element(all(v))
#define MAX(v) *max_element(all(v))
#define overload2(_1, _2, name, ...) name
#define vec(type, name, ...) vector<type> name(__VA_ARGS__)
#define vv(type, name, h, ...) vector<vector<type>> name(h, vector<type>(__VA_ARGS__))
#define vvv(type, name, h, w, ...) vector<vector<vector<type>>> name(h, vector<vector<type>>(w, vector<type>(__VA_ARGS__)))

constexpr int mod = 998244353;

template< int mod >
struct NumberTheoreticTransform {
    
    vector< int > rev, rts;
    int base, max_base, root;
    
    NumberTheoreticTransform() : base(1), rev{0, 1}, rts{0, 1} {
        assert(mod >= 3 && mod % 2 == 1);
        auto tmp = mod - 1;
        max_base = 0;
        while(tmp % 2 == 0) tmp >>= 1, max_base++;
        root = 2;
        while(mod_pow(root, (mod - 1) >> 1) == 1) ++root;
        assert(mod_pow(root, mod - 1) == 1);
        root = mod_pow(root, (mod - 1) >> max_base);
    }
    
    inline int mod_pow(int x, int n) {
        int ret = 1;
        while(n > 0) {
            if(n & 1) ret = mul(ret, x);
            x = mul(x, x);
            n >>= 1;
        }
        return ret;
    }
    
    inline int inverse(int x) {
        return mod_pow(x, mod - 2);
    }
    
    inline unsigned add(unsigned x, unsigned y) {
        x += y;
        if(x >= mod) x -= mod;
        return x;
    }
    
    inline unsigned mul(unsigned a, unsigned b) {
        return 1ull * a * b % (unsigned long long) mod;
    }
    
    void ensure_base(int nbase) {
        if(nbase <= base) return;
        rev.resize(1 << nbase);
        rts.resize(1 << nbase);
        for(int i = 0; i < (1 << nbase); i++) {
            rev[i] = (rev[i >> 1] >> 1) + ((i & 1) << (nbase - 1));
        }
        assert(nbase <= max_base);
        while(base < nbase) {
            int z = mod_pow(root, 1 << (max_base - 1 - base));
            for(int i = 1 << (base - 1); i < (1 << base); i++) {
                rts[i << 1] = rts[i];
                rts[(i << 1) + 1] = mul(rts[i], z);
            }
            ++base;
        }
    }
    
    void ntt(vector< int > &a) {
        const int n = (int) a.size();
        assert((n & (n - 1)) == 0);
        int zeros = __builtin_ctz(n);
        ensure_base(zeros);
        int shift = base - zeros;
        for(int i = 0; i < n; i++) {
            if(i < (rev[i] >> shift)) {
                swap(a[i], a[rev[i] >> shift]);
            }
        }
        for(int k = 1; k < n; k <<= 1) {
            for(int i = 0; i < n; i += 2 * k) {
                for(int j = 0; j < k; j++) {
                    int z = mul(a[i + j + k], rts[j + k]);
                    a[i + j + k] = add(a[i + j], mod - z);
                    a[i + j] = add(a[i + j], z);
                }
            }
        }
    }
    
    vector< int > multiply(vector< int > a, vector< int > b) {
        int need = a.size() + b.size() - 1;
        int nbase = 1;
        while((1 << nbase) < need) nbase++;
        ensure_base(nbase);
        int sz = 1 << nbase;
        a.resize(sz, 0);
        b.resize(sz, 0);
        ntt(a);
        ntt(b);
        int inv_sz = inverse(sz);
        for(int i = 0; i < sz; i++) {
            a[i] = mul(a[i], mul(b[i], inv_sz));
        }
        reverse(a.begin() + 1, a.end());
        ntt(a);
        a.resize(need);
        return a;
    }
};

void mpl(int &x,int y) {
    x += y;
    if(x >= mod) x -= mod;
}

int dp[200200][2];

NumberTheoreticTransform<mod>ntt;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    string s;
    cin >> n >> s;
    vvc<pii>ki(n);
    rep(i,n-1) {
        int u,v;
        cin >> u >> v;
        u--;
        v--;
        ki[u].pb({v,0});
        ki[v].pb({u,1});
    }
    auto calc = [&](vc<pii>a) {
        int N = si(a);
        vvc<int>tmp(N);
        rep(i,N) {
            tmp[i].pb(a[i].fi);
            tmp[i].pb(a[i].se);
        }
        vc<int>id(N);
        iota(all(id),0);
        while(si(id) > 1) {
            vc<int>nxt;
            for(int i = 0; i < si(id); i += 2) {
                if(i+1 == si(id)) {
                    nxt.pb(id[i]);
                    continue;
                }
                tmp[id[i]] = ntt.multiply(tmp[id[i]],tmp[id[i+1]]);
                nxt.pb(id[i]);
            }
            id = nxt;
        }
        return tmp[id[0]];
    };
    auto dfs = [&](auto &dfs,int n,int p) -> void {
        vc<pii>a,b;
        a.pb({1,0});
        b.pb({1,0});
        if(s[n] == 'S') {
            a.pb({1,1});
        }
        else {
            b.pb({1,1});
        }
        int f = -1;
        for(auto i:ki[n]) {
            if(i.first == p) {
                f = i.se;
                continue;
            }
            dfs(dfs,i.first,n);
            if(i.se == 0) {
                b.pb({dp[i.fi][0],dp[i.fi][1]});
            }
            else {
                a.pb({dp[i.fi][0],dp[i.fi][1]});
            }
        }
        vc<int>x = calc(a);
        vc<int>y = calc(b);
        if(f == -1) {
            int ans = 0;
            rep(i,min(si(x),si(y))) {
                mpl(ans,1ll*x[i]*y[i]%mod);
            }
            cout << ans << "\n";
            return;
        }
        if(f == 0) {
            rep(i,min(si(x),si(y))) {
                mpl(dp[n][0],1ll*x[i]*y[i]%mod);
            }
            rep(i,1,min(si(x),si(y)+1)) {
                mpl(dp[n][1],1ll*x[i]*y[i-1]%mod);
            }
            return;
        }
        if(f == 1) {
            rep(i,min(si(x),si(y))) {
                mpl(dp[n][0],1ll*x[i]*y[i]%mod);
            }
            rep(i,1,min(si(x)+1,si(y))) {
                mpl(dp[n][1],1ll*x[i-1]*y[i]%mod);
            }
            return;
        }
    };
    dfs(dfs,0,-1);
}