#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
string s = "0";
int res;
int dp[200005];
vector <int> graf[200005];
void dfs(int v, int par){
int mx = 0;
for(auto c : graf[v]){
if(c == par) continue;
dfs(c, v);
dp[v] += dp[c];
mx = max(mx, dp[c]);
}
if(s[v] == '1') res = max(res, 1+mx);
else res = max(res, dp[v]);
dp[v] -= s[v]-'0';
if(dp[v] <= 0 && s[v] == '1') dp[v] = 1;
//cout << v << " " << dp[v] << endl;
res = max(res, dp[v]);
}
int main(){
ios_base::sync_with_stdio(false), cin.tie(0);
cout.precision(10);
cout << fixed;
int n;
cin >> n;
for(int i=1; i<n; i++){
int a, b;
cin >> a >> b;
graf[a].push_back(b);
graf[b].push_back(a);
}
string g;
cin >> g;
s += g;
dfs(1, 0);
cout << res;
return 0;
}
