#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << " " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << " " << j << " " << #i << " " << q << " " << #p << endl;
#define show4(x,y) for(auto it:y) cout << it << " "; cout << #x << endl;
typedef pair<int,int>pii;
typedef pair<pii,pii>pi2;
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
int n;
vector<int>adj[200005];
int best=0;
int dp[200005];
string s;
void dfs(int index, int par){
for(auto it:adj[index]){
if(it==par) continue;
dfs(it,index);
}
int maxi=0;
for(auto it:adj[index]){
if(it==par) continue;
dp[index]+=max(0LL,dp[it]);
maxi=max(maxi,dp[it]);
}
if(s[index]=='1'){
//show(val,maxi+1);
best=max(best,maxi+1);
}
if(s[index]=='1'){
dp[index]=max(dp[index]-1,1LL);
}
//show2(index,index,dp[index],dp[index]);
best=max(best,dp[index]);
}
void solve(){
int n;
cin >> n;
int temp,temp2;
for(int x=0;x<n-1;x++){
cin >> temp >> temp2;
adj[temp].push_back(temp2);
adj[temp2].push_back(temp);
}
cin >> s;
s=" "+s;
dfs(1,-1);
cout << best;
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
int t=1;
//cin >> t;
while(t--){
solve();
}
}
