#undef _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define pb push_back
#define fi first
#define si second
#define ar array
using lint = long long;
typedef pair<int,int> pi;
typedef tuple<int,int,int> ti;
void debug_out() {cerr<<endl;}
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {cerr<<" "<<to_string(H);debug_out(T...);}
#define debug(...) cerr<<"["<<#__VA_ARGS__<<"]:",debug_out(__VA_ARGS__)
int N, ans;
vector<int> adj[200010];
char S[200010];
int dp[200010][2];
void dfs(int x, int p) {
int sum = 0, mx = 0;
for (auto i: adj[x]) {
if (i == p) continue;
dfs(i, x);
sum += dp[i][0];
mx = max(mx, dp[i][0]);
}
if (S[x] == '1') {
dp[x][1] = max(mx + 1, 1);
dp[x][0] = max(sum - 1, 1);
} else {
dp[x][0] = sum;
dp[x][1] = sum;
}
}
int main() {
fast;
cin >> N;
for (int i = 1; i < N; ++i) {
int u, v; cin >> u >> v;
adj[u].pb(v);
adj[v].pb(u);
}
for (int i = 1; i <= N; ++i) cin >> S[i];
dfs(1, -1);
for (int i = 1; i <= N; ++i) ans = max({ans, dp[i][0], dp[i][1]});
cout << ans;
return 0;
}
