#include <bits/stdc++.h>
using namespace std;
int main() {
// freopen("main.in", "r", stdin);
// freopen(".out", "w", stdout);
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n; cin >> n;
vector<vector<int>> g(n + 1);
for (int i = 0; i < n - 1; i++) {
int a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
string s; cin >> s;
s = " " + s;
vector<long long> dp(n + 1, 0);
vector<int> par(n + 1, 0);
vector<int> ord;
queue<int> q;
q.push(1);
par[1] = -1;
while (!q.empty()) {
int u = q.front(); q.pop();
ord.push_back(u);
for (int v : g[u]) if (v != par[u]) { par[v] = u; q.push(v); }
}
for (int k = n - 1; k >= 0; k--) {
int u = ord[k];
long long sum = 0, best = LLONG_MIN;
for (int v : g[u]) if (v != par[u]) {
sum += dp[v];
if (dp[v] > best) best = dp[v];
}
if (s[u] == '1') {
long long a = (best == LLONG_MIN ? 1 : best + 1);
long long b = sum - 1;
dp[u] = max(a, b);
} else {
dp[u] = sum;
}
}
cout << dp[1] << endl;
}
