#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define SZ(x) (int((x).size()))
#define rep(i,a,b) for(int (i)=(a);(i)<=(b);(i)++)
#define rep2(i,a,b) for(int (i)=(a);(i)<(b);(i)++)
#define Rep(p,x) for(int (p)=head[(x)];(p);(p)=nxt[(p)])
const int maxn=2e5+5;
long long ans;
int n,tot,all;
int f[maxn],g[maxn],cnt[maxn],mx[maxn],se[maxn],high[maxn],low[maxn];
char s[maxn];
vector<int>e[maxn];
void dfs1(int x,int fa){
	mx[x]=f[x]=0;
	cnt[x]=(s[x]=='1');
	rep2(i,0,SZ(e[x])){
		int y=e[x][i];
		if(y==fa)continue;
		dfs1(y,x);
		f[x]=max(f[y]+1,f[x]);
		if(f[y]+1>mx[x])se[x]=mx[x],mx[x]=f[y]+1;
		else if(f[y]+1>se[x])se[x]=f[y]+1;
		cnt[x]+=cnt[y];
	}
}
void dfs2(int x,int fa){
	rep2(i,0,SZ(e[x])){
		int y=e[x][i];
		if(y==fa)continue;
		g[y]=max((f[y]+1==mx[x]?se[x]:mx[x]),g[x])+1;
		dfs2(y,x);
	}
}
void dfs3(int x,int fa){
	if(g[x]>mx[x])se[x]=mx[x],mx[x]=g[x];
	else if(g[x]>se[x])se[x]=g[x];
	high[x]=min(se[x]+1,mx[x]-1);
	low[x]=high[x]+1;
	rep2(i,0,SZ(e[x])){
		int y=e[x][i];
		if(y==fa)continue;
		dfs3(y,x);
		if(cnt[y])low[x]=min(low[x],f[y]+1);
	}
	if(all-cnt[x])low[x]=min(low[x],g[x]);
	if(s[x]=='1')low[x]=0;
}
int main(){
	scanf("%d",&n);
	rep(i,1,n-1){
		int x,y;scanf("%d%d",&x,&y);
		e[x].pb(y);e[y].pb(x);
	}
	scanf("%s",s+1);
	rep(i,1,n)all+=(s[i]=='1');
	dfs1(1,0);dfs2(1,0);dfs3(1,0);
	rep(x,1,n)ans+=high[x]-low[x]+1;
	printf("%lld\n",ans+1);
	return 0;
}