#include<bits/stdc++.h>
#define sqr(x) ((x)*(x))
#define ll long long
#define ull unsigned long long
#define ui unsigned int
#define ld long double
#define vi vector<int>
#define HEAP(...) priority_queue<__VA_ARGS__ >
#define heap(...) priority_queue<__VA_ARGS__,vector<__VA_ARGS__ >,greater<__VA_ARGS__ > > 
#define pii pair<int,int> 
#define pb push_back
#define mp make_pair
#define debuge cerr<<"isok"<<endl
#define debug(x) cerr<<#x<<"="<<x<<endl
#define dprintf(...) fprintf(stderr,__VA_ARGS__)
#define SS second
#define FF first
#define ls (k<<1)
#define rs (k<<1|1)
#define clr(a,x) memset(a,x,sizeof(a))
#define cpy(a,x) memcpy(a,x,sizeof(a))
#define file(x) freopen(x".in","r",stdin),freopen(x".out","w",stdout)
#define SZ(x) ((int)x.size())
using namespace std;
template<class T> inline void gmin(T &x,const T &y){if(x>y) x=y;}
template<class T> inline void gmax(T &x,const T &y){if(x<y) x=y;}
const int BufferSize=1<<16;
char buffer[BufferSize],*Bufferhead,*Buffertail;
bool Terminal;
inline char Getchar(){
	if(Bufferhead==Buffertail){
		int l=fread(buffer,1,BufferSize,stdin);
		if(!l){Terminal=1;return 0;}
		Buffertail=(Bufferhead=buffer)+l;
	}
	return *Bufferhead++;
}
template<class T>inline bool read(T &x){
	x=0;char c=Getchar(),rev=0;
	while(c<'0'||c>'9'){c=Getchar();rev|=c=='-';if(Terminal)return 0;}
	while(c>='0'&&c<='9') x=x*10+c-'0',c=Getchar();
	if(c=='.'){
		c=Getchar();double t=0.1;
		while(c>='0'&&c<='9') x=x+(c-'0')*t,c=Getchar(),t=t/10;
	}
	x=rev?-x:x;
	return 1;
}
template<class T1,class T2> inline bool read(T1 &x,T2 &y){return read(x)&read(y);}
template<class T1,class T2,class T3> inline bool read(T1 &x,T2 &y,T3 &z){return read(x)&read(y)&read(z);}
template<class T1,class T2,class T3,class T4> inline bool read(T1 &x,T2 &y,T3 &z,T4 &w){return read(x)&read(y)&read(z)&read(w);}
inline bool reads(char *x){
	char c=Getchar();
	while(c<33||c>126){c=Getchar();if(Terminal)return 0;}
	while(c>=33&&c<=126) (*x++)=c,c=Getchar();
	*x=0;return 1;
}
template<class T>inline void print(T x,const char c='\n'){
	if(!x){putchar('0');putchar(c);return;}
	if(x<0) putchar('-'),x=-x;
	int m=0,a[20];
	while(x) a[m++]=x%10,x/=10;
	while(m--) putchar(a[m]+'0');
	putchar(c);
}
//--------------------------------head---------------------------------------------

const int inf=0x3f3f3f3f;
const int N=200005,M=100005,mod=1e9+7;
template<class T,class S> inline void ch(T &x,const S y){x=(x+y)%mod;}
inline int exp(int x,int y,const int mod=::mod){
	int ans=1;
	while(y){
		if(y&1) ans=(ll)ans*x%mod;
		x=(ll)x*x%mod;y>>=1;
	}return ans;
}

int n,m,mx[N],mx2[N],si[N];
ll ans=1;
vi g[N];
char s[N];

inline void pre(int x,int f=0){
	si[x]=(s[x]=='1');m+=si[x];
	for(int y:g[x]){
		if(y==f) continue;
		pre(y,x);
		if(mx[y]+1>mx[x]) mx2[x]=mx[x],mx[x]=mx[y]+1;
		else if(mx[y]+1>mx2[x]) mx2[x]=mx[y]+1;
		si[x]+=si[y];
	}
}
inline void dfs(int x,int f=0,int k=0){
	int a=mx[x],b=mx2[x];
	if(k>a) b=a,a=k; else if(k>b) b=k;
	if(s[x]=='1') ans+=min(b+1,a-1)+1;
	else{
		int mn=min(b+1,a-1)+1;
		if(m-si[x]) gmin(mn,k);
		for(int y:g[x])
			if(si[y]) gmin(mn,mx[y]+1);
		ans+=min(b+1,a-1)-mn+1;
	}
	for(int y:g[x]){
		if(y==f) continue;
		dfs(y,x,max(k,mx[y]+1==mx[x]?mx2[x]:mx[x])+1);
	}
}

int main(){
#ifdef rqgao2014
	freopen("input.txt","r",stdin);
#endif
	read(n);
	for(int i=1;i<n;i++){
		int x,y;read(x,y);
		g[x].pb(y);g[y].pb(x);
	}
	reads(s+1);
	pre(1);dfs(1);
	print(ans);
	return 0;
}

Measured memory_bytes: 21376