//#pragma optimization_level 3
//#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include<bits/stdc++.h>
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>
using namespace __gnu_pbds;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>ordset;
*/
#define fr first
#define sc second
#define vec vector
#define pb push_back
#define pii pair<int, int>
#define forn(x,y) for(int x = 1 ; x <= (int)y ; ++x)
#define all(x) (x).begin(),(x).end()
#define fast cin.tie(0);cout.tie(0);cin.sync_with_stdio(0);cout.sync_with_stdio(0);
using namespace std;
typedef long long ll;
typedef unsigned int uint;
typedef pair<ll,ll> pll;
typedef complex<int> point;
const int nmax = 200005;
const ll linf = 1e18;
const ll mod = 998244353;
const int inf = 1e9+10;
const int sq = 5000;
int n;
char asd[nmax];
int viz[nmax];
vec < int > g[nmax] , ng[nmax];
vec < pii > edges;
map < pair<int,int> , pair < int,int> > dp;
int compute_dp(int nod1 , int nod2){
if(dp[{nod1,nod2}].sc > 0){
//cout << "dp: " << nod1 << ' '<< nod2 << ' '<< dp[{nod1,nod2}].fr << '\n';
return dp[{nod1,nod2}].fr;
}
int rs = -(asd[nod2] == '1') , rs2 = (asd[nod2] == '1');
for(int i : g[nod2]){
if(i != nod1){
rs+= compute_dp(nod2,i);
}
}
dp[{nod1,nod2}] = {max(rs,rs2),1};
//cout << "dp: " << nod1 << ' '<< nod2 << ' '<< max(rs,rs2) << '\n';
return max(rs,rs2);
}
int main(){
cin >> n;
for(int i = 1; i < n; i++){
int a, b;
cin >> a >> b;
g[a].pb(b);
g[b].pb(a);
edges.pb({a,b});
}
int cnt = 0;
for(int i = 1; i <= n; i++){
cin >> asd[i];
cnt += (asd[i] == '1');
}
int rez;
if(cnt >= 2){
rez = 2;
}else{
rez = 1;
}
for(int i = 1; i <= n; i++){
int rs;
//cout << "COMPUTE " << i << '\n';
if(asd[i] == '1')rs = -1;
else rs = 0;
//cout << rs << '\n';
for(int j : g[i]){
rs += compute_dp(i,j);
}
//cout << i << ' ' << rs << '\n';
rez = max(rez,rs);
}
cout << rez << '\n';
}
