/**
____ ____ ____ ____ ____
||a |||t |||o |||d |||o ||
||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|
**/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N_MAX = 200000;
int N;
vector <int> adj[N_MAX + 2];
bool plant[N_MAX + 2];
int answer;
int dp[N_MAX + 2];
void dfs (int u, int parent = -1) {
for (int v : adj[u]) {
if (v != parent) {
dfs(v, u);
dp[u] += dp[v];
}
}
answer = max(answer, dp[u] - plant[u] + (parent != -1 && plant[parent] == true));
if (plant[u] == true) {
dp[u] = max(dp[u] - 1, 1);
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> N;
for (int i = 1; i <= N - 1; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
string str;
cin >> str;
for (int u = 1; u <= N; u++) {
plant[u] = (str[u - 1] == '1');
}
dfs(1);
cout << answer << "\n";
return 0;
}
