#include<bits/stdc++.h>
using namespace std;
const int nax = (int)2e5 + 10;
bool isGen[nax];
vector<int> g[nax];
int ans;
int dp[nax];
void dfs(int u, int par){
if(isGen[u]){
int best = 0;
for(int v : g[u]) if(v != par){
dfs(v, u);
dp[u] += dp[v];
best = max(best, dp[v] + 1); // use the Generator on v.
}
ans = max(ans, best);
dp[u]--; // because i have generator and it will break
dp[u] = max(dp[u], 1); // it will break only if i have > 2.
} else {
for(int v : g[u]) if(v != par){
dfs(v, u);
dp[u] += dp[v];
}
ans = max(ans, dp[u]);
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
for(int i = 1;i < n;i++){
int a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
for(int i = 1;i <= n;i++){
char c; cin >> c;
if(c == '1') isGen[i] = 1;
}
dfs(1, -1);
cout << ans << '\n';
return 0;
}
