#include<bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,tune=native")
using namespace std;
const int N = 1e5 * 5ll;
typedef long long ll;
string s;
vector<ll>g[N];
ll ans = 0ll;
ll dp[N];
void dfs(ll v, ll p){
if(s[v - 1] == '1'){
for(auto to : g[v]){
if(to != p){
dfs(to, v);
dp[v] = dp[v] + dp[to];
// just take subtree of child so ->>...
ans = max(ans, dp[to] + 1ll);
}
}
if(dp[v] >= 2ll){
dp[v] -= 1ll;
}
else{
dp[v] = max(dp[v], 1ll);
}
// because v will break;
}
else{
for(auto to : g[v]){
if(to != p){
dfs(to, v);
dp[v] += dp[to];
// just take subtree of child so ->>...
ans = max(ans, dp[to] + 0ll);
}
}
}
ans = max(ans, dp[v]);
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
ll n;
cin >> n;
for(ll i = 1; i <= n - 1; ++i){
ll a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
cin >> s;
dfs(1ll, -1ll);
cout << ans << endl;
return 0;
}
