#include <bits/stdc++.h>
using namespace std;
#define int long long
class tree {
int n;
vector <int> dp;
vector <vector <int>> gr;
string is;
int ans = 0;
void dfs(int num, int last) {
int counter = 0;
for (int next : gr[num]) {
if (next != last) {
dfs(next, num);
if (dp[next] > 0) {
++counter;
}
dp[num] += dp[next];
}
}
if (is[num] == '1') {
if (counter < 2) {
ans = max(ans, dp[num] + 1);
}
dp[num] = max(dp[num] - 1, 1LL);
}
ans = max(ans, dp[num]);
}
public:
void init() {
cin >> n;
dp.resize(n);
gr.resize(n);
for (int i = 0; i < n - 1; ++i) {
int a, b;
cin >> a >> b;
--a;
--b;
gr[a].push_back(b);
gr[b].push_back(a);
}
cin >> is;
}
void get_ans() {
dfs(0, 0);
cout << ans << '\n';
}
};
void solve() {
tree now;
now.init();
now.get_ans();
}
signed main() {
cin.tie(0);
ios::sync_with_stdio(false);
solve();
}
