#include<bits/stdc++.h>
using namespace std;
vector<int> ad[200005];
int dp[200005], a[200005], ans = 0;
bool visited[200005];
void dfs(int u)
{
visited[u] = 1;
for(int v : ad[u]) if(visited[v] == 0){
dfs(v); dp[u] += dp[v];
}
if(a[u] == 1){
dp[u] = max(dp[u] - 1, 1); ans = max(ans, 1);
for(int v : ad[u]) if(visited[v] == 0) ans = max(ans, dp[v] + 1);
}
else ans = max(ans, dp[u]);
visited[u] = 0;
//cerr<<"A"<<u<<" "<<dp[u]<<endl;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
int n; cin>>n;
for(int i = 0; i < n-1; i++){
int u, v; cin>>u>>v;
ad[u].push_back(v);
ad[v].push_back(u);
}
int num = 0;
for(int i = 1; i <= n; i++){
char x; cin>>x;
a[i] = (x == '1'); num += a[i];
}
dfs(1);
cout<<ans;
}
