#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define rep(a, b) for(int a = 0; a < (b); ++a)
#define st first
#define nd second
#define pb push_back
#define all(a) a.begin(), a.end()
const int LIM=2e5+7;
vector<int>V[LIM];
int dp[LIM], ans;
string S;
void DFS(int x, int o) {
for(auto i : V[x]) if(i!=o) {
DFS(i, x);
if(S[x]=='1') ans=max(ans, dp[i]+1);
dp[x]+=dp[i];
}
if(S[x]=='1') --dp[x];
dp[x]=max(dp[x], S[x]-'0');
ans=max(ans, dp[x]);
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
int n;
cin >> n;
rep(i, n-1) {
int a, b;
cin >> a >> b; --a; --b;
V[a].pb(b);
V[b].pb(a);
}
cin >> S;
DFS(0, 0);
cout << ans << '\n';
}
