#include"bits/stdc++.h"


#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fr(x) freopen(x,"r",stdin)
#define fw(x) freopen(x,"w",stdout)
#define iout(x) printf("%d\n",x)
#define lout(x) printf("%lld\n",x)
#define REP(x,l,u) for(ll x = (l);x<=(u);x++)
#define RREP(x,l,u) for(ll x = (l);x>=(u);x--)
#define mst(x,a) memset(x,a,sizeof(x))
#define PII pair<int,int>
#define PLL pair<ll,ll>
#define MP make_pair
#define se second
#define fi first
#define dbg(x) cout<<#x<<" = "<<(x)<<endl;
#define sz(x) ((int)x.size())
#define cl(x) x.clear()

typedef  long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;
using namespace std;

const int maxn = 200010;
const int mod = 1e9+7;
const double eps = 1e-6;
const double PI = acos(-1);

template<typename T> inline void read(T &x){
x=0;T f=1;char ch;do{ch=getchar();if(ch=='-')f=-1;}while(ch<'0'||ch>'9');do x=x*10+ch-'0',ch=getchar();while(ch<='9'&&ch>='0');x*=f;
}

template<typename A,typename B> inline void read(A&x,B&y){read(x);read(y);}
template<typename A,typename B,typename C> inline void read(A&x,B&y,C&z){read(x);read(y);read(z);}
template<typename A,typename B,typename C,typename D> inline void read(A&x,B&y,C&z,D&w){read(x);read(y);read(z);read(w);}
template<typename A,typename B> inline A fexp(A x,B p){A ans=1;for(;p;p>>=1,x=1LL*x*x%mod)if(p&1)ans=1LL*ans*x%mod;return ans;}
template<typename A,typename B> inline A fexp(A x,B p,A mo){A ans=1;for(;p;p>>=1,x=1LL*x*x%mo)if(p&1)ans=1LL*ans*x%mo;return ans;}

int n;

char st[maxn];

vector<int> G[maxn];

int f[maxn],g[maxn],low[maxn],high[maxn];

void dfs1(int u,int fa){
	low[u]=st[u]=='1'?0:n;
	for(auto v:G[u])if(v!=fa){
		dfs1(v,u);
		f[u]=max(f[u],f[v]+1);
		low[u]=min(low[u],max(low[v],f[v])+1);//move down and touch the bottom
	}
}

void dfs2(int u,int fa){
	int mx=g[u],se=0;
	for(auto v:G[u])if(v!=fa){
		se=max(se,f[v]+1);
		if(se>mx)swap(mx,se);
	}
	high[u]=min(se+1,max(f[u],g[u])-1);
	for(auto v:G[u])if(v!=fa){
		if(f[v]==mx-1)g[v]=se+1,low[v]=min(low[v],max(low[u],se)+1);
		else g[v]=mx+1,low[v]=min(low[v],max(low[u],mx)+1);
		dfs2(v,u);
	}
}

void Work(){
	dfs1(1,0);
	dfs2(1,0);
	ll ans=0;
	REP(i,1,n)ans+=max(0,high[i]-low[i]+1);
	cout<<ans+1<<endl;
}

void Init(){
	read(n);
	REP(i,2,n){
		int u,v;read(u,v);
		G[u].PB(v);G[v].PB(u);
	}
	scanf("%s",st+1);
}

int main(){
	Init();
	Work();
	return 0;
}
