#include <bits/stdc++.h>
#define fi first
#define se second
#define sajz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
const int N = 2e5+7;
string type; int n, dp[N], res = 0;
vector<int> g[N];
void dfs(int v, int par){
int mx = 0;
for (auto u : g[v]){
if (u == par) continue;
dfs(u, v);
dp[v] += dp[u];
mx = max(mx, dp[u]);
}
if (type[v-1] == '1'){
dp[v] = max(1, dp[v] - 1);
res = max(res, mx + 1);
}
res = max(res, dp[v]);
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
for (int i=0; i<n-1; i++){
int a, b; cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
cin >> type;
dfs(1, 1);
//for (int i=1; i<=n; i++) cout << i << ": " << dp[i] << '\n';
cout << res << '\n';
return 0;
}
/*
6
2 3
4 3
1 3
3 5
6 2
110011
*/
