#include<bits/stdc++.h>
#define MAXN 200007
using namespace std;
int n,a,b,ans,dp[MAXN],cnt;
int down[MAXN],up[MAXN],sdown[MAXN],sup[MAXN];
char c[MAXN];
vector<int> v[MAXN];
void dfs(int x,int p){
down[x]=c[x]-'0';
int sum=0;
for(int i:v[x]){
if(i==p)continue;
dfs(i,x);
sum+=down[i];
}
sdown[x]=sum;
down[x]=max(down[x] , sum-down[x]);
}
void dfs2(int x,int p){
int loss=c[x]-'0';
if(p!=0){
sup[x]=max( (c[p]-'0') - loss , sup[p] + sdown[p] - down[x] - loss );
}else sup[x]=-loss;
for(int i:v[x]){
if(i==p)continue;
dfs2(i,x);
}
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n;
for(int i=1;i<=n-1;i++){
cin>>a>>b;
v[a].push_back(b);
v[b].push_back(a);
}
for(int i=1;i<=n;i++){
cin>>c[i];
if(c[i]=='1')cnt++;
}
ans=min(cnt,2);
dfs(1,0);
dfs2(1,0);
for(int i=1;i<=n;i++){
ans=max(ans, sdown[i] + sup[i]);
}
ans=min(ans,cnt);
cout<<ans<<"\n";
return 0;
}
