#include <cstdio>
#include <cstring>
#include <algorithm>
#define inf 0x7fffffff

using namespace std;

typedef long long ll;

struct Edge {
  int t,next;
  Edge() {}
  Edge(int a,int b):t(a),next(b) {}
};

Edge e[400005];
int head[200005];
bool num[200005];

int dep[200005],dep2[200005],dis[200005],size[200005];
bool in[200005];

void dfs1(int x,int fa) {
  size[x]=in[x]=num[x];
  dis[x]=(num[x])?0:inf;
  for(int i=head[x];i;i=e[i].next)
    if (e[i].t!=fa) {
    	int u=e[i].t;
    	dfs1(u,x);
    	in[x]|=in[u];
    	if (dep[u]+1>=dep[x]) {
    		dep2[x]=dep[x];dep[x]=dep[u]+1;
		}
		else dep2[x]=max(dep2[x],dep[u]+1);
    	if (in[u]) dis[x]=min(dis[x],dep[u]+1);
    	size[x]+=size[u];
	}
}

int up[200005],cnt;
ll ans;

void dfs2(int x,int fa) {
  ans+=max(min(dep[x],dep2[x]+2)-dis[x],0);
  int max1=up[x],max2=0;
  for(int i=head[x];i;i=e[i].next)
    if (e[i].t!=fa) {
    	int u=e[i].t;
    	if (dep[u]+1>=max1) {
    		max2=max1;max1=dep[u]+1;
		}
		else max2=max(max2,dep[u]+1);
	}
  for(int i=head[x];i;i=e[i].next)
    if (e[i].t!=fa) {
    	int u=e[i].t;
    	up[u]=(dep[u]+1==max1)?max2+1:max1+1;
    	if (up[u]>=dep[u]) {
    		dep2[u]=dep[u];dep[u]=up[u];
		}
		else dep2[u]=max(dep2[u],up[u]);
    	if (cnt-size[u]) dis[u]=min(dis[u],up[u]);
    	dfs2(u,x);
	}
}

char s[200005];

int main() {
  int n;
  scanf("%d",&n);
  for(int i=1;i<n;i++) {
  	int x,y;
  	scanf("%d%d",&x,&y);
  	e[2*i-1]=Edge(y,head[x]);
  	head[x]=2*i-1;
  	e[2*i]=Edge(x,head[y]);
  	head[y]=2*i;
  }
  scanf("%s",s+1);
  for(int i=1;i<=n;i++) {
  	num[i]=(s[i]=='1');
  	cnt+=num[i];
  }
  dfs1(1,0);
  dfs2(1,0);
  printf("%lld\n",ans+1);
  return 0; 
}