#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
typedef long long ll;
typedef pair<long long, long long> pll;
typedef pair<int,int> pii;
typedef vector<long long> vl;
typedef vector<int> vi;
bool generator[200100];
vi G[200100];
int dp[200100][2], n, ans = 0;
void dfs(int at, int p){
dp[at][0] = dp[at][1] = 0;
int all = 0, max1 = 0, max0 = 0;
for(auto next : G[at]){
if(next == p) continue;
dfs(next, at);
all += dp[next][0];
max1 = max(max1, dp[next][1]);
max0 = max(max0, dp[next][0]);
}
if(generator[at]){
dp[at][0] = max(1, all - 1);
dp[at][1] = max0 + 1;
}
else{
dp[at][0] = all;
dp[at][1] = max1;
}
ans = max(ans, dp[at][0]);
ans = max(ans, dp[at][1]);
}
int main(){
cin>>n;
for(int i = 1; i < n; i++){
int a, b;
cin>>a>>b;
a--; b--;
G[a].pb(b);
G[b].pb(a);
}
for(int i = 0; i < n; i++){
char a;
cin>>a;
if(a == '1') generator[i] = true;
else generator[i] = false;
}
dfs(0, -1);
cout<<ans<<endl;
return 0;
}
