#include"bits/stdc++.h"
using namespace std;
#ifndef EVAL
#define dbg(x) cout<<#x<<" := " <<x<<endl;
#define dbgv(x) \
for(int vv=0;vv<x.size();vv++){if(vv)cout<<" ";\
cout<<x[vv];\
}\
cout<<endl;\
#else
#define dbg(x) (void)x
#define dbgv(x) (void)x
#endif
using ll=long long;
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define drep(i,n) for(ll i=ll(n)-1;i>=0;i--)
#define REP(i,n,m) for(ll i=(ll)(n);i<(ll)(m);i++)
#define DREP(i,n,m) for(ll i=(ll)(n);i>=(ll)(m);i--)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
template<class T>using vc=vector<T>;
template<class T>using vvc=vc<vc<T>>;
template<class T,class F>
int chmin(T&a,F b){
if(a>b){
a=b;
return 1;
}
return 0;
}
template<class T,class F>
int chmax(T&a,F b){
if(a<b){
a=b;
return 1;
}
return 0;
}
void solve(){
int n;
cin>>n;
vvc<int>g(n);
rep(i,n-1){
int a,b;
cin>>a>>b;
g[--a].push_back(--b);
g[b].push_back(a);
}
string s;
cin>>s;
int ans=0;
auto dfs=[&](auto&dfs,int u,int v)->int{
ll sm=0;
ll mx=0;
for(auto&x:g[u]){
if(x==v)continue;
auto res=(dfs(dfs,x,u));
sm+=res;
chmax(mx,res);
}
if(s[u]=='1'){
chmax(ans,mx+1);
chmax(ans,sm-1);
sm=max<int>(1,sm-1);
}else{
chmax(ans,sm);
}
return sm;
};
dfs(dfs,0,-1);
cout<<ans<<"\n";
}
int main(){
#ifndef EVAL
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
#endif
cin.tie(0)->sync_with_stdio(0);
solve();
}
/*
2*on-シュタイナー木のsizeがうれしさ
dp[v]:=v を塗った時のmax
*/
