#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e18+7;
const ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<ll,ii>
#define ull unsigned ll
#define f(i,a,b) for(ll i = a;i < b;i++)
#define pb push_back
#define vll vector<ll>
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
///I hope I will get uprating and don't make mistakes
///I will never stop programming
///sqrt(-1) Love C++
///Please don't hack me
///@TheofanisOrfanou Theo830
///Think different approaches (bs,dp,greedy,graphs,shortest paths,mst)
///Stay Calm
///Look for special cases
///Beware of overflow and array bounds
///Think the problem backwards
///Training
ll dp[200005][2];
vector<vll>adj;
string s;
ll solve(ll idx,ll par,bool ep){
if(dp[idx][ep] != -1){
return dp[idx][ep];
}
ll ans = s[idx - 1] - '0';
if(ep){
ll res = -ans;
for(auto x:adj[idx]){
if(x != par){
res += solve(x,idx,ep);
}
}
ans = max(ans,res);
}
else{
ans = 0;
for(auto x:adj[idx]){
if(x != par){
ans = max(ans,solve(x,idx,0));
}
}
if(s[idx - 1] == '1'){
ll res = 1;
for(auto x:adj[idx]){
if(x != par){
res = max(res,1 + solve(x,idx,1));
}
}
ans = max(ans,res);
}
ll res = -(s[idx - 1] - '0');
for(auto x:adj[idx]){
if(x != par){
res += solve(x,idx,1);
}
}
ans = max(ans,res);
}
return dp[idx][ep] = ans;
}
int main(void){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll n;
cin>>n;
memset(dp,-1,sizeof dp);
adj.assign(n+5,vll());
f(i,0,n-1){
ll a,b;
cin>>a>>b;
adj[a].pb(b);
adj[b].pb(a);
}
cin>>s;
cout<<solve(1,0,0)<<"\n";
}
