#include<bits/stdc++.h>
#define rep(i,s,t) for(register int i=s;i<=t;++i)
using namespace std;
#define RI register int
int read(){
    int q=0;char ch=' ';
    while(ch<'0'||ch>'9') ch=getchar();
    while(ch>='0'&&ch<='9') q=q*10+ch-'0',ch=getchar();
    return q;
}
typedef long long LL;
const int N=200005,inf=0x3f3f3f3f;
int h[N],ne[N<<1],to[N<<1],mx[N],se[N],d[N],sz[N];
int n,tot;
LL ans;
char S[N];
inline void add(int x,int y){to[++tot]=y,ne[tot]=h[x],h[x]=tot;}
inline void dfs1(int x,int las){
    if(S[x]=='1')d[x]=0,sz[x]=1;
    else d[x]=inf;
    for(RI i=h[x];i;i=ne[i]){
        if(to[i]==las)continue;
        int y=to[i];dfs1(y,x),sz[x]+=sz[y];
        if(mx[y]+1>mx[x])se[x]=mx[x],mx[x]=mx[y]+1;
        else if(mx[y]+1>se[x])se[x]=mx[y]+1;
        if(sz[y])d[x]=min(d[x],mx[y]+1);
    }
}
inline void dfs2(int x,int las){
    int R=min(se[x]+1,mx[x]-1);
    if(d[x]<=R)ans+=(LL)(R-d[x]+1);
    for(RI i=h[x];i;i=ne[i]){
        if(to[i]==las)continue;
        int y=to[i],kl=(mx[y]+1==mx[x]?se[x]+1:mx[x]+1);
        if(kl>mx[y])se[y]=mx[y],mx[y]=kl;
        else if(kl>se[y])se[y]=kl;
        if(sz[1]-sz[y])d[y]=min(d[y],kl);
        dfs2(y,x);
    }
}
int main(){
    int x,y;
    n=read();
    rep(i,2,n)x=read(),y=read(),add(x,y),add(y,x);
    scanf("%s",S+1);
    dfs1(1,0),dfs2(1,0);
    printf("%lld\n",ans+1);
    return 0;
}