#include<bits/stdc++.h>
using namespace std;
#define pb push_back
const int MXN = 2e5+5;
int n;
vector<int> g[MXN];
int dp[MXN], ans;
string s;
void dfs(int v, int p=0) {
for(int u : g[v])
if(u!=p)
dfs(u, v);
for(int u : g[v])
if(u!=p)
dp[v] += dp[u];
ans = max(ans, dp[v]);
if(s[v]=='1') {
for(int u : g[v])
if(u!=p)
ans = max(ans, dp[u]+1);
dp[v] = max(1, dp[v]-1);
ans = max(ans, dp[v]);
}
}
int32_t main() {
cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
cin >> n;
for(int i=1,u,v; i<n; i++) {
cin >> u >> v;
g[u].pb(v);
g[v].pb(u);
}
cin >> s;
s = "0" + s;
dfs(1);
cout << ans << '\n';
return 0;
}
