#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ull unsigned long long
#define ld long double
#define pii pair<int, int>
#define fi first
#define se second
#define __builtin_popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(x) ((1ll << (x)))
#define debug(a, l, r) for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n';
const int MAXN = 2e5 + 5;
int n, dp[MAXN], res = 0;
string s;
vector<int> adj[MAXN];
void dfs(int u, int par = -1) {
int cand = - (s[u] == '1');
for (int v : adj[u]) {
if (v == par) continue;
dfs(v, u);
res = max(res, (s[u] == '1') + dp[v]);
cand += dp[v];
}
dp[u] = max((int)(s[u] == '1'), cand);
}
signed main() {
#ifdef NCTHANH
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
cin >> n;
for (int i = 1; i < n; ++i) {
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
cin >> s; s = ' ' + s;
dfs(1);
cout << max(res, *max_element(dp + 1, dp + n + 1));
return 0;
}
