#include <bits/stdc++.h>
#define ALL(X) begin(X), end(X)
using i64 = long long;
using namespace std;
template <class T>
using vec = vector<T>;
template <class T>
istream& operator>>(istream& is, vec<T>& X) {
for (auto& x : X) {
is >> x;
}
return is;
}
template <class T>
constexpr T infty = 0;
template <>
constexpr int infty<int> = 1'000'000'000;
template <>
constexpr i64 infty<i64> = 1'000'000'000'000'000'000;
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
int N; cin >> N;
vec<vec<int>> g(N);
for (int i = 0; i < N - 1; i++) {
int u, v; cin >> u >> v;
u -= 1, v -= 1;
g[u].emplace_back(v);
g[v].emplace_back(u);
}
string s; cin >> s;
int ans{};
auto dfs = [&](auto&& dfs, int x, int pre) -> int {
int sum{}, mx{};
for (auto to : g[x]) {
if (to == pre) {
continue;
}
int d = dfs(dfs, to, x);
sum += d;
mx = max(mx, d);
}
if (s[x] == '1') {
ans = max(ans, mx + 1);
ans = max(ans, sum - 1);
}
else {
ans = max(ans, sum);
}
return max((int)(s[x] == '1'), max(mx, sum) - (s[x] == '1'));
};
dfs(dfs, 0, -1);
cout << ans << '\n';
}
