#include<algorithm>
#include<cstring>
#include<cctype>
#include<cstdio>
#define rep(i,x,y) for(int i=x; i<=y; ++i)
#define repd(i,x,y) for(int i=x; i>=y; --i)

using namespace std;
const int N=200005;
char s[N];
int n,h[N],cnt,siz[N],mx[N],mx2[N],mn[N];
typedef long long LL;
LL ans;
struct edge{int v,n;} e[N<<1];

int getint()
{
	char ch;
	while(!isdigit(ch=getchar()));
	int x=ch-48;
	while(isdigit(ch=getchar())) x=x*10+ch-48;
	return x;
}

void addedge(int u,int v)
{
	e[cnt]=(edge){v,h[u]},h[u]=cnt++;
	e[cnt]=(edge){u,h[v]},h[v]=cnt++;
}

void pushup(int x,int y)
{
	if(mx[x]<y) mx2[x]=mx[x],mx[x]=y;
	else mx2[x]=max(mx2[x],y);
}

void dfs1(int x,int fa)
{
	if(s[x]=='1') siz[x]=1,mn[x]=0;
	for(int i=h[x]; i!=-1; i=e[i].n)
		if(e[i].v!=fa)
		{
			dfs1(e[i].v,x);
			siz[x]+=siz[e[i].v];
			if(siz[e[i].v]) mn[x]=min(mn[x],mx[e[i].v]+1);
			pushup(x,mx[e[i].v]+1);
		}
}

void dfs2(int x,int fa)
{
	if(fa)
	{
		int tmp;
		if(mx[fa]==mx[x]+1) tmp=mx2[fa]+1; else tmp=mx[fa]+1;
		if(siz[1]-siz[x]>0) mn[x]=min(mn[x],tmp);
		pushup(x,tmp);
	}
	for(int i=h[x]; i!=-1; i=e[i].n)
		if(e[i].v!=fa)
			dfs2(e[i].v,x);
	ans+=max(0,min(mx[x]-1,mx2[x]+1)-mn[x]+1);
}		

int main()
{
	n=getint();
	memset(h,-1,sizeof(h));
	rep(i,1,n-1) addedge(getint(),getint());
	rep(i,1,n) mn[i]=n;
	scanf("%s",s+1);
	dfs1(1,0),dfs2(1,0);
	printf("%lld\n",ans+1);
	return 0;
}