#include<bits/stdc++.h>
using namespace std;
const int N = 200'000;
#define vec vector
#define pb push_back
int dp[N][2];
vec<int> tree[N];
string s;
void dfs(int u, int p = -1) {
for(int v : tree[u]) {
if(p==v) continue;
dfs(v, u);
}
int a = 1; int b = -1; int c = 0;
for(int v : tree[u]) {
if(v==p) continue;
a = max(dp[v][1]+1, a);
b += dp[v][1];
c = max(dp[v][0], c);
}
if(s[u] == '1') {
dp[u][0] = max(max(a, b), c);
dp[u][1] = max(b, 1);
}
else {
dp[u][1] = b+1;
dp[u][0] = max(c, b+1);
}
}
int main() {
int n;
cin >> n;
for(int i = 0; i<n-1; i++) {
int u, v;
cin >> u >> v;
u--; v--;
tree[u].pb(v);
tree[v].pb(u);
}
cin >> s;
dfs(0);
cout << dp[0][0] << '\n';
}
