#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pll pair<int, int>
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define endl '\n'
#define ld long double
signed main(){
int n;cin>>n;
vector<vector<int>> al(n+1);
for(int i=0;i<n-1;i++){
int a,b;cin>>a>>b;
al[a].pb(b);
al[b].pb(a);
}
vector<bool> s(n+1);
for(int i=1;i<=n;i++){
char c;cin>>c;
if(c=='1')s[i]=1;
else s[i]=0;
}
vector<int> dp(n+1, 0);
auto dfs=[&](auto && dfs, int x, int p)->void{
int sm=0;
for(auto it:al[x]){
if(it==p)continue;
dfs(dfs,it,x);
sm+=dp[it];
}
if(s[x])dp[x]=max(1ll, sm-1);
else dp[x]=sm;
};
dfs(dfs, 1, 0);
vector<int> res(n+1, 0);
auto reroot=[&](auto && reroot, int x, int p, int pv)->void{
int sm=pv;
for(auto it:al[x]){
if(it==p)continue;
sm+=dp[it];
}
if(s[x])res[x]=max(1ll, sm-1);
else res[x]=sm;
for(auto it:al[x]){
if(it==p)continue;
if(s[x])reroot(reroot, it, x, max(1ll, sm-dp[it]-1));
else reroot(reroot, it, x, sm-dp[it]);
}
};
reroot(reroot, 1, 0, 0);
cout<<*max_element(res.begin(),res.end());
}
