//Code by dXqwq, who is still searching painless suicide.
#include<bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#define int long long
using namespace std;
namespace Polynomial
{
	using ll=long long;
	using poly=vector<ll>;
	const ll mod=998244353;
	ll ksm(ll a,ll b)
	{
		ll ans=1;
		while(b)
		{
			if(b&1) ans=ans*a%mod;
			b>>=1;
			a=a*a%mod;
		}
		return ans;
	}
	inline int sz(const poly &p)
	{
		return p.size();
	}
	const poly operator +(const poly &a,const poly &b)
	{
		int p=sz(a),q=sz(b);
		int n=max(p,q);
		poly ret(n,0);
		for(int i=0;i<n;i++)
		{
			if(i<p) ret[i]+=a[i];
			if(i<q) ret[i]+=b[i];
			if(ret[i]>=mod) ret[i]-=mod;
		}
		return ret;
	}
	const poly operator -(const poly &a,const poly &b)
	{
		int p=sz(a),q=sz(b);
		int n=max(p,q);
		poly ret(n,0);
		for(int i=0;i<n;i++)
		{
			if(i<p) ret[i]+=a[i];
			if(i<q) ret[i]+=mod-b[i];
			if(ret[i]>=mod) ret[i]-=mod;
		}
		return ret;
	}
	poly operator *(poly a,poly b)
	{
		const ll g=3;
		int len=sz(a)+sz(b);
		int m=1;
		while(m<sz(a)+sz(b)) m*=2;
		a.resize(m);
		b.resize(m);
		vector<int> rev(m);
		for(int i=0;i<m;i++)
			rev[i]=(rev[i>>1]>>1)|((i&1)*(m>>1));
		for(int i=0;i<m;i++)
			if(rev[i]<i)
			{
				swap(a[i],a[rev[i]]);
				swap(b[i],b[rev[i]]);
			}
		for(int i=1;i<m;i<<=1)
		{
			ll gn=ksm(g,(mod-1)/i/2);
			for(int j=0;j<m;j+=(i<<1))
			{
				ll g0=1;
				for(int k=0;k<i;k++,g0=g0*gn%mod)
				{
					{
						ll x=a[j+k],y=g0*a[i+j+k]%mod;
						a[j+k]=(x+y)%mod;
						a[i+j+k]=(x+mod-y)%mod;
					}
					{
						ll x=b[j+k],y=g0*b[i+j+k]%mod;
						b[j+k]=(x+y)%mod;
						b[i+j+k]=(x+mod-y)%mod;
					}
				}
			}
		}
		for(int i=0;i<m;i++)
			a[i]=a[i]*b[i]%mod;
		for(int i=0;i<m;i++)
			if(rev[i]<i)
				swap(a[i],a[rev[i]]);
		for(int i=1;i<m;i<<=1)
		{
			ll gn=ksm(g,(mod-1)/i/2*(mod-2));
			for(int j=0;j<m;j+=(i<<1))
			{
				ll g0=1;
				for(int k=0;k<i;k++,g0=g0*gn%mod)
				{
					ll x=a[j+k],y=g0*a[i+j+k]%mod;
					a[j+k]=(x+y)%mod;
					a[i+j+k]=(x+mod-y)%mod;
				}
			}
		}
		ll val=ksm(m,mod-2);
		for(int i=0;i<m;i++)
			a[i]=a[i]*val%mod;
		a.resize(len-1);
		return a;
	}
	poly inv(poly p,int deg)
	{
		p.resize(deg);
		if(deg==1) return {ksm(p[0],mod-2)};
		poly w=inv(p,(deg+1)/2);
		poly g=w+w-p*w*w;
		g.resize(deg);
		return g;
	}
	poly deriv(poly p)
	{
		for(int i=0;i<sz(p);i++)
			p[i]=p[i]*i%mod;
		p.erase(p.begin());
		return p;
	}
	poly integ(poly p)
	{
		p.insert(p.begin(),0);
		for(int i=0;i<sz(p);i++)
			p[i]=p[i]*ksm(i,mod-2)%mod;
		return p;
	}
	poly ln(poly p)
	{
		return integ(deriv(p)*inv(p,sz(p)));
	}
	poly exp(poly p,int deg)
	{
		p.resize(deg);
		if(deg==1)
			return {1};
		poly g=exp(p,(deg+1)/2);
		g=g*(poly{1}-ln(g)+p);
		g.resize(deg);
		return g;
	}
	const poly operator %(poly a,poly b)
	{
		if(sz(a)<sz(b)) return a;
		int n=sz(a),m=sz(b);
		int d=n-m+1;
		poly a2=a,b2=b;
		reverse(a2.begin(),a2.end());
		reverse(b2.begin(),b2.end());
		a2.resize(d);
		b2.resize(d);
		poly q=a2*inv(b2,d);
		q.resize(d);
		reverse(q.begin(),q.end());
		q=a-b*q;
		q.resize(m-1);
		return q;
	}
	const poly operator /(poly a,poly b)
	{
		if(sz(a)<sz(b)) return a;
		int n=sz(a),m=sz(b);
		int d=n-m+1;
		poly a2=a,b2=b;
		reverse(a2.begin(),a2.end());
		reverse(b2.begin(),b2.end());
		a2.resize(d);
		b2.resize(d);
		poly q=a2*inv(b2,d);
		q.resize(d);
		reverse(q.begin(),q.end());
		return q;
	}
}
using namespace Polynomial;
inline int read(){
   int s=0,w=1;
   char ch=getchar();
   while(ch<'0'||ch>'9'){if(ch=='-')w=-1;ch=getchar();}
   while(ch>='0'&&ch<='9') s=s*10+ch-'0',ch=getchar();
   return s*w;
}
const int p=998244353;
vector<pair<int,int>> e[1<<20];
char s[1<<20];
int f[1<<20],g[1<<20];
vector<int> mulall(vector<vector<int>> &A)
{
	if(A.empty()) return {1};
	while(A.size()>1)
	{
		int sz=A.size(),mid=(sz+1)>>1;
		for(int i=mid; i<sz; ++i)
			A[i-mid]=A[i]*A[i-mid];
		A.resize(mid);
	}
	return A[0];
}
void dfs(int x,int fa=0,int ty=1)
{
	vector<vector<int>> P,N;	
	for(auto [y,z]:e[x]) if(y!=fa)
	{
		dfs(y,x,z);	
		if(z==1) P.push_back({f[y],g[y]});
		else N.push_back({f[y],g[y]});
	}
	
	vector<int> X=mulall(P);
	vector<int> Y=mulall(N);
	
	int sx=X.size();
	int sy=Y.size();
	
	for(int i=0; i<sx&&i<sy; ++i)
		f[x]=(f[x]+1ll*X[i]*Y[i])%p;
	
		
	// if(ty==1&&s[x]=='F') g[x]=f[x];
	// if(ty==-1&&s[x]=='S') g[x]=f[x];

	if(s[x]=='S')
	{
		for(int i=0; i+1<sx&&i<sy; ++i)
			f[x]=(f[x]+1ll*X[i+1]*Y[i])%p;
		if(ty==1)
		{
			for(int i=0; i+2<sx&&i<sy; ++i)
			g[x]=(g[x]+1ll*X[i+2]*Y[i])%p;
		}
		else
		{
			for(int i=0; i<sx&&i<sy; ++i)
			g[x]=(g[x]+1ll*X[i]*Y[i])%p;
		}
	}
		
	if(s[x]=='F') 
	{
		for(int i=0; i<sx&&i+1<sy; ++i)
			f[x]=(f[x]+1ll*X[i]*Y[i+1])%p;
		if(ty==1)
		{
			for(int i=0; i<sx&&i<sy; ++i)
			g[x]=(g[x]+1ll*X[i]*Y[i])%p;
		}
		else
		{
			for(int i=0; i<sx&&i+2<sy; ++i)
			g[x]=(g[x]+1ll*X[i]*Y[i+2])%p;
		}
	}
	
	if(ty==1)
	{
		for(int i=0; i+1<sx&&i<sy; ++i)
		g[x]=(g[x]+1ll*X[i+1]*Y[i])%p;
	}
	else
	{
		for(int i=0; i<sx&&i+1<sy; ++i)
		g[x]=(g[x]+1ll*X[i]*Y[i+1])%p;
	}
	
	 // printf("%d %d %d %d\n",x,ty,f[x],g[x]);
	return ;
}
signed main()
{
	int n=read();
	scanf("%s",s+1);
	for(int i=1; i<n; ++i)
	{
		int u=read(),v=read();
		e[u].push_back({v,1}),
		e[v].push_back({u,-1});
	}
	dfs(1);
	printf("%lld\n",f[1]);
	return 0;
}