/*
Things to notice:
1. do not calculate useless values
2. do not use similar names
 
Things to check:
1. submit the correct file
2. time (it is log^2 or log)
3. memory
4. prove your naive thoughts 
5. long long
6. corner case like n=0,1,inf or n=m
7. check if there is a mistake in the ds or other tools you use
8. fileio in some oi-contest

9. module on time 
10. the number of a same divisor in a math problem
11. multi-information and queries for dp and ds problems
*/
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fi first
#define se second
#define pii pair<long long,long long>
#define mp make_pair
#define pb push_back
const int mod=998244353;
const int inf=0x3f3f3f3f;
const int INF=1e18;
int fpow(int x,int b)
{
	if(b==0) return 1;
	if(x==0) return 0;
	int res=1;
	while(b>0)
	{
		if(b&1)	res=1LL*res*x%mod;
		x=1LL*x*x%mod;
		b>>=1;
	}
	return res;
}
struct Mypoly
{
	int n,m;
	int a[2200005],b[2200005],p[2200005],c[2200005];
	int N=1,lg;
	// ntt
	void ntt(int *A)
	{
		for(int i=0;i<N;i++) if(i<p[i]) swap(A[i],A[p[i]]);
		for(int mid=1;mid<N;mid*=2)
		{
			int v=fpow(3,(mod-1)/(mid*2));
			for(int j=0;j<N;j+=mid*2)
			{
				int w=1;
				for(int k=0;k<mid;k++,w=(w*v)%mod)
				{
					int t1=A[j+k],t2=(w*A[j+k+mid])%mod;
					A[j+k]=(t1+t2)%mod,A[j+k+mid]=(t1-t2+mod)%mod;
				}
			}
		}
	}
	void intt(int *A)
	{
		for(int i=0;i<N;i++) if(i<p[i]) swap(A[i],A[p[i]]);
		for(int mid=1;mid<N;mid*=2)
		{
			int v=fpow(fpow(3,mod-2),(mod-1)/(mid*2));
			for(int j=0;j<N;j+=mid*2)
			{
				int w=1;
				for(int k=0;k<mid;k++,w=(w*v)%mod)
				{
					int t1=A[j+k],t2=(w*A[j+k+mid])%mod;
					A[j+k]=(t1+t2)%mod,A[j+k+mid]=(t1-t2+mod)%mod;
				}
			}
		}
		int inv=fpow(N,mod-2);
		for(int i=0;i<=n+m;i++) A[i]=A[i]*inv%mod;
	}
	void init_butterfly(int x)
	{
		N=1,lg=0;
		while(N<x) N*=2,lg++;
		for(int i=1;i<N;i++) p[i]=(p[i>>1]>>1)|((i&1)<<(lg-1));
	} 
	// poly mul 
	vector <int> mul(vector <int> P,vector <int> Q)
	{
	//	memset(a,0,sizeof(a)),memset(b,0,sizeof(b)),memset(p,0,sizeof(p));
		n=P.size()-1,m=Q.size()-1;
		for(int i=0;i<=n;i++) a[i]=P[i];
		for(int i=0;i<=m;i++) b[i]=Q[i];
		init_butterfly(n+m+1);
		ntt(a),ntt(b);
		for(int i=0;i<N;i++) a[i]=(a[i]*b[i])%mod;
		intt(a);
		vector <int> res;
		res.clear();
		for(int i=0;i<=n+m;i++) res.pb(a[i]);
		for(int i=0;i<=2*N;i++) a[i]=b[i]=p[i]=0;
		return res;
	}
	// poly inv
	void work_getinv(int deg)
	{
		if(deg==1) 
		{
			b[0]=fpow(a[0],mod-2);
			return;
		}
		work_getinv((deg+1)>>1);
		init_butterfly(deg<<1);
		for(int i=0;i<deg;i++) c[i]=a[i];
		for(int i=deg;i<N;i++) c[i]=0;
		ntt(c),ntt(b);
		for(int i=0;i<N;i++) b[i]=1LL*(2-1LL*c[i]*b[i]%mod+mod)%mod*b[i]%mod;
		intt(b);
		for(int i=deg;i<N;i++) b[i]=0;
	}
	vector <int> getinv(vector <int> P)
	{
		n=P.size();
	//	memset(a,0,sizeof(a)),memset(b,0,sizeof(b)),memset(p,0,sizeof(p));
		for(int i=0;i<n;i++) a[i]=P[i];
		work_getinv(n);
		vector <int> Q;
		for(int i=0;i<n;i++) Q.pb(b[i]);
		for(int i=0;i<=2*N;i++) a[i]=b[i]=p[i]=0;
		return Q;
	}
}poly;
int n;
string S;
int sz[200005],tp[200005],L[200005],R[200005];
vector <pii > g[200005],dp[200005];
void dfs1(int u,int fa)
{
	sz[u]=(S[u]=='F');
	for(int i=0;i<g[u].size();i++)
	{
		int v=g[u][i].fi;
		if(v==fa)
		{
			if(g[u][i].se==1) tp[u]=1;
			else tp[u]=-1;
		}
		else dfs1(v,u),sz[u]+=sz[v]; 
	}
	if(u==1) L[u]=R[u]=sz[u];
	else if(tp[u]==1) L[u]=sz[u],R[u]=sz[u]+1;
	else R[u]=sz[u],L[u]=max(0LL,sz[u]-1);
}
vector <int> ps[200005];
void dfs2(int u,int fa)
{
	vector <int> ss;
	for(int i=0;i<g[u].size();i++)
	{
		int v=g[u][i].fi;
		if(v==fa) continue;
		dfs2(v,u);
		ss.pb(v);
	}
	int del=0;
	priority_queue <pii,vector<pii >,greater<pii > > pq;
	for(int i=0;i<ss.size();i++) 
	{
		del+=L[ss[i]];
		ps[i].clear(),ps[i].resize(2);
		int v=ss[i];
		for(int j=0;j<dp[v].size();j++) ps[i][dp[v][j].fi-L[v]]=(ps[i][dp[v][j].fi-L[v]]+dp[v][j].se);
		pq.push(mp(2LL,i));
	}
	ps[ss.size()].resize(2);
	ps[ss.size()][0]=ps[ss.size()][1]=1;
	pq.push(mp(2LL,1LL*ss.size()));
	while(pq.size()>1)
	{
		int x=pq.top().se;
		pq.pop();
		int y=pq.top().se;
		pq.pop();
		ps[y]=poly.mul(ps[x],ps[y]),pq.push(mp(1LL*ps[y].size(),y));
	}
	int id=pq.top().se;
	for(int i=0;i<ps[id].size();i++) if(L[u]<=i+del&&i+del<=R[u]) dp[u].pb(mp(i+del,ps[id][i]));
}
void solve()
{
	cin>>n;
	cin>>S;
	S='.'+S;
	for(int i=1;i<n;i++)
	{
		int u,v;
		cin>>u>>v;
		g[u].pb(mp(v,1)),g[v].pb(mp(u,-1));
	}
	dfs1(1,-1);
	dfs2(1,-1);
	if(dp[1].size()) cout<<dp[1][0].se<<"\n";
}
signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int _=1;
//	cin>>_;
	while(_--) solve();
	return 0;
}