#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<ll,ll>
#define pii pair<int,int>
#define fs first
#define sc second
#define tlll tuple<ll,ll,ll>
const int mxn = 2e5+10;
int dp[mxn];
string s;
vector<int> tree[mxn];
int N;
int ans = 0;
void dfs(int now,int par){
dp[now] = s[now]-'0';
int mx = 0,down = 0;
for(auto nxt:tree[now]){
if(nxt == par)continue;
dfs(nxt,now);
mx = max(mx,dp[nxt]);
down += max(dp[nxt],0);
}
ans = max({mx+dp[now],down-dp[now],ans});
dp[now] = max(dp[now],down-dp[now]);
return;
}
int main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>N;
for(int i = 1;i<N;i++){
int a,b;
cin>>a>>b;
tree[a].push_back(b);
tree[b].push_back(a);
}
cin>>s;
s = "#"+s;
dfs(1,1);
cout<<ans<<'\n';
return 0;
}
