#include<bits/stdc++.h>
using namespace std;
const int MAX_SOM=200*1000+5;
int nbSom,debAre,finAre,rep;
vector<int> adja[MAX_SOM];
int val[MAX_SOM],dv[MAX_SOM];
string etatDeb;
int DFS(int pos) {
if (dv[pos]==0) {
dv[pos]=1;
int somme=0,maxi=0,ans;
for (int i:adja[pos]) {
ans=DFS(i);
somme+=ans;
maxi=max(maxi,ans);
}
//cout<<pos<<" "<<maxi<<" "<<somme<<endl;
rep=max(rep,max(maxi+val[pos],somme-val[pos]));
return max(somme-val[pos],val[pos]);
}
else {
return 0;
}
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
cin>>nbSom;
for (int i=0;i<nbSom-1;i++) {
cin>>debAre>>finAre;
adja[debAre].push_back(finAre);
adja[finAre].push_back(debAre);
}
cin>>etatDeb;
for (int i=1;i<=nbSom;i++) {
if (etatDeb[i-1]=='1') {
val[i]=1;
}
}
DFS(1);
cout<<rep<<endl;
return 0;
}
