//####################
//PowerPlant
//####################
#include<bits/stdc++.h>
using namespace std;
const int maxiN = 2*1e5;
bool isPowerPlant[maxiN];
vector<int> links[maxiN];
int dp[2][maxiN];
int solve(bool cm,int node,int dad=-1){
if(dp[cm][node]!=-1)return dp[cm][node];
int re = 0;
if(isPowerPlant[node])re=1;
int malus = (cm && isPowerPlant[node]?1:0);
for(int v:links[node])if(v!=dad){
re = max(re, solve(false,v,node) - malus);
}
int sum = 0;
for(int v:links[node])if(v!=dad){
sum += solve(true,v,node);
}
sum -=malus;
// le malus prcq ça va se faire péter
return dp[cm][node] = max(re,sum) ;
}
signed main(){
ios::sync_with_stdio(false);
int n;cin>>n;
for(int i = 1;i<n;i++){
int a,b;cin>>a>>b;
a--;
b--;
links[a].push_back(b);
links[b].push_back(a);
}
fill(dp[0],dp[0]+n,-1);
fill(dp[1],dp[1]+n,-1);
string binary;cin>>binary;
for(int i= 0;i<n;i++)isPowerPlant[i] = (binary[i]=='1');
int ans = max(solve(0,0),solve(1,0));
for(int i = 0;i<1;i++){
if(isPowerPlant[i]){
for(int v:links[i])if(v!=i){
ans = max(ans, 1+solve(1,v,i));
}
}
}
cout<<ans<<endl;
return 0;
};
