#include<iostream>
#include<cstdio>
#define N (300000+1000)
using namespace std;

struct Edge{int to,next;}edge[N<<1];
int head[N],num_edge,Maxdep[N],size[N],sum,n,u,v;
long long ans;
char s[N];

void add(int u,int v)
{
	edge[++num_edge].to=v;
	edge[num_edge].next=head[u];
	head[u]=num_edge;
}

void Dfs1(int x,int fa)
{
	size[x]=(s[x]=='1');
	for (int i=head[x]; i; i=edge[i].next)
		if (edge[i].to!=fa)
		{
			Dfs1(edge[i].to,x);
			size[x]+=size[edge[i].to];
			Maxdep[x]=max(Maxdep[x],Maxdep[edge[i].to]+1);
		}
}

void Dfs2(int x,int fa,int maxdis)
{
	int l=(s[x]=='1'?0:(1<<30)), r, max1=maxdis, max2=0;
	if (sum-size[x]) l=min(l,maxdis);
	for (int i=head[x]; i; i=edge[i].next)
		if (edge[i].to!=fa)
		{
			if (Maxdep[edge[i].to]+1>max2) max2=Maxdep[edge[i].to]+1;
			if (max2>max1) swap(max1,max2);
			if (size[edge[i].to]) l=min(l,Maxdep[edge[i].to]+1);
		}
	if (max1==max2) r=max2-1;
	else if (max1==max2+1) r=max2;
	else r=max2+1;
	if (l<=r) ans+=r-l+1;
	for (int i=head[x]; i; i=edge[i].next)
		if (edge[i].to!=fa)
		{
			if (Maxdep[edge[i].to]+1!=max1) Dfs2(edge[i].to,x,max1+1);
			else Dfs2(edge[i].to,x,max2+1);
		}
}

int main()
{
	scanf("%d",&n);
	for (int i=1; i<n; ++i)
	{
		scanf("%d%d",&u,&v);
		add(u,v); add(v,u);
	}
	scanf("%s",s+1);
	for (int i=1; i<=n; i++)  sum+=(s[i]=='1');
	Dfs1(1,0); Dfs2(1,0,0);
	printf("%lld\n",ans+1);
}