#include <bits/stdc++.h>
using namespace std;
#define ref(i,x,y)for(int i=x;i<=y;++i)
#define pb push_back
#define SZ(x) ((int)x.size())
typedef vector<int> vec;
typedef long long LL;
const int N=200010;
char Read(){
	char c=getchar();
	while(c<'0'||c>'1')c=getchar();
	return c;
}
int read(){
	char c=getchar();int d=0,f=1;
	for(;c<'0'||c>'9';c=getchar())if(c=='-')f=-1;
	for(;c>='0'&&c<='9';d=d*10+c-48,c=getchar());
	return d*f;
}
LL ans;
int n,s[N],w[N],dep[N],Dep[N],g[N][2];
vec e[N];
void add(int x,int y){e[x].pb(y);e[y].pb(x);}
void dfs1(int f,int x){
	ref(i,0,SZ(e[x])-1){int y=e[x][i];
		if(y==f)continue;
		dfs1(x,y);dep[x]=max(dep[x],dep[y]);s[x]+=s[y];
	}
	dep[x]++;s[x]+=w[x];
}
void dfs2(int f,int x){
	int&D1=g[x][0],&D2=g[x][1];
	D1=Dep[x];D2=0;
	int mi=N;if(s[1]-s[x]>0)mi=Dep[x];
	ref(i,0,SZ(e[x])-1){int y=e[x][i];
		if(y==f)continue;
		if(s[y])mi=min(mi,dep[y]);
		if(dep[y]>D1)D2=D1,D1=dep[y];else
		if(dep[y]>D2)D2=dep[y];
	}
	ref(i,0,SZ(e[x])-1){int y=e[x][i];
		if(y==f)continue;
		if(dep[y]==D1)Dep[y]=D2+1;
		else Dep[y]=D1+1;
		dfs2(x,y);
	}
	if(w[x])ans+=min(D1,D2)+1;else
		ans+=max(0,min(D1,D2)-mi+1);
	if(x>1)ans+=(dep[x]<=Dep[x]&&s[x]>0||Dep[x]<=dep[x]&&s[1]-s[x]>0);
}
int main(){
	n=read();
	ref(i,2,n)add(read(),read());
	ref(i,1,n)w[i]=Read()-'0';
	dfs1(0,1);dfs2(0,1);
	cout<<ans<<endl;
}