#include <bits/stdc++.h>
#define uwu return 0;
using namespace std;
const int SIZE = 2e5 + 5;
vector <int> graph[SIZE];
int dp[2][SIZE];
bool is_power[SIZE];
void dfs(int nd, int rt){
for(auto i:graph[nd]){
if(i == rt)
continue;
dfs(i, nd);
if(is_power[nd]){
dp[0][nd] = max({dp[0][nd], dp[0][i], dp[1][i] + 1});
dp[1][nd] += max({0, dp[1][i]});
}
else{
dp[0][nd] = max({dp[0][nd], dp[0][i]});
dp[1][nd] += max({0, dp[1][i]});
}
}
if(is_power[nd]){
dp[0][nd] = max({dp[0][nd], dp[1][nd] - 1, 1});
dp[1][nd] = max({dp[1][nd] - 1 , 1});
}
else{
dp[0][nd] = max({dp[0][nd], dp[1][nd]});
}
return;
}
int main(){
int N;
cin >> N;
for (int a, b, i = 1; i < N; i++){
cin >> a >> b;
graph[a].push_back(b);
graph[b].push_back(a);
}
for (int i = 1; i <= N; i++){
char c;
cin >> c;
is_power[i] = (c == '1');
}
dfs(1, 0);
cout << dp[0][1] << '\n';
uwu
}
