#include<bits/stdc++.h>
using namespace std;
#define REP(i,st,ed) for(register int i=st,i##end=ed;i<=i##end;++i)
#define DREP(i,st,ed) for(register int i=st,i##end=ed;i>=i##end;--i)
typedef long long ll;
template<typename T>inline bool chkmin(T &x,T y){return (y<x)?(x=y,1):0;}
template<typename T>inline bool chkmax(T &x,T y){return (y>x)?(x=y,1):0;}
inline int read(){
	int x;
	char c;
	int f=1;
	while((c=getchar())!='-' && (c>'9' || c<'0'));
	if(c=='-') f=-1,c=getchar();
	x=c^'0';
	while((c=getchar())>='0' && c<='9') x=(x<<1)+(x<<3)+(c^'0');
	return x*f;
}
inline ll readll(){
	ll x;
	char c;
	int f=1;
	while((c=getchar())!='-' && (c>'9' || c<'0'));
	if(c=='-') f=-1,c=getchar();
	x=c^'0';
	while((c=getchar())>='0' && c<='9') x=(x<<1ll)+(x<<3ll)+(c^'0');
	return x*f;
}
const int maxn=2e5+10,inf=0x3f3f3f3f;
int Begin[maxn],Next[maxn<<1],to[maxn<<1],e;
inline void add_edge(int x,int y){
	to[++e]=y;
	Next[e]=Begin[x];
	Begin[x]=e;
}
int Md[maxn],g[maxn],Md1[maxn],g1[maxn];
int sz[maxn],Up[maxn],Down[maxn];
char s[maxn];
void dfs1(int x,int ff){
	Md1[x]=inf,sz[x]=(s[x]=='1');
	for(int i=Begin[x];i;i=Next[i]) if(to[i]!=ff){
		dfs1(to[i],x),sz[x]+=sz[to[i]];
		chkmax(Md[x],Md[to[i]]+1);
		if(sz[to[i]]) chkmin(Md1[x],Md[to[i]]+1);
	}
	if(s[x]=='1') chkmin(Md1[x],Md[x]);
}
void dfs2(int x,int ff){
	int Max=0,Sec=0;
	Up[x]=max(g[x],Md[x])-1;
	Down[x]=min(Md1[x],sz[x]==sz[1]?inf:g[x]);
	if(s[x]=='1') Down[x]=0;
	chkmin(Up[x],Md[x]+1);
	for(int i=Begin[x];i;i=Next[i]) if(to[i]!=ff){
		if(Md[to[i]]+1>Max) Sec=Max,Max=Md[to[i]]+1;
		else chkmax(Sec,Md[to[i]]+1);
	}
	for(int i=Begin[x];i;i=Next[i]) if(to[i]!=ff){
		g[to[i]]=g[x];
		if(Md[to[i]]+1==Max) chkmax(g[to[i]],Sec);
		else chkmax(g[to[i]],Max);
		++g[to[i]];
		chkmin(Up[x],g[to[i]]);
	}
	for(int i=Begin[x];i;i=Next[i]) if(to[i]!=ff) dfs2(to[i],x);
}
int main(){
	int n=read();
	REP(i,1,n-1){
		int x=read(),y=read();
		add_edge(x,y),add_edge(y,x);
	}
	scanf("%s",s+1);
	ll ans=0;
	REP(i,1,n) ans|=(s[i]=='1');
	dfs1(1,0),g1[1]=inf;
	dfs2(1,0);
	REP(i,1,n) if(Down[i]<=Up[i]) ans+=Up[i]-Down[i]+1;
	printf("%lld\n",ans);
	return 0;
}
