#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 2e5 + 10;
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
vector<vector<int>> g(n);
for (int i = 0; i < n - 1; ++i) {
int x, y;
cin >> x >> y;
x--; y--;
g[x].push_back(y);
g[y].push_back(x);
}
string s;
cin >> s;
int ans = 0;
vector<int> dp(n, 0);
function<void(int, int)> dfs = [&] (int x, int p) {
int c = 0, mx = 0;
for (auto y: g[x]) {
if (y != p) {
dfs(y, x);
c += dp[y];
mx = max(mx, dp[y]);
}
}
if (s[x] == '1') {
ans = max(ans, 1 + mx);
ans = max(ans, c - 1);
dp[x] = max(1, max(c - 1, mx - 1));
} else {
dp[x] = max(c, 0);
ans = max(ans, dp[x]);
}
};
dfs(0, -1);
// for (int i = 0; i < n; ++i) cout << dp[i] << '\n';
cout << ans << "\n";
}
