//雪花飄飄北風嘯嘯
//天地一片蒼茫
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl
#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()
#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
int n;
vector<int> al[200005];
string s;
map<ii,int> memo;
int par[200005];
int val[200005];
int dfs(int i,int p){
if (memo.count(ii(i,p))) return memo[ii(i,p)];
int res=0;
if (par[i]==-2){
for (auto &it:al[i]){
if (it==p) continue;
res+=dfs(it,i);
}
par[i]=p;
val[i]=res;
}
else{
res=val[i];
if (par[i]!=-1) res+=dfs(par[i],i);
if (p!=-1) res-=dfs(p,i);
}
res+=(s[i]=='1'?-1:0);
return memo[ii(i,p)]=max(res,(s[i]=='1'?1:0));
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin.exceptions(ios::badbit | ios::failbit);
cin>>n;
rep(x,0,n) par[x]=-2;
int a,b;
rep(x,1,n){
cin>>a>>b;
a--,b--;
al[a].push_back(b);
al[b].push_back(a);
}
cin>>s;
int ans=0;
rep(x,0,n) if (s[x]=='1') ans++;
ans=min(ans,2);
rep(x,0,n){
ans=max(dfs(x,-1),ans);
}
cout<<ans<<endl;
}
