#include <bits/stdc++.h>
#define pb push_back
#define endl ("\n")
#define all(aa) aa.begin(), aa.end()
typedef long long ll;
using namespace std;
int main(){
int n;
cin >> n;
vector<vector<int>> g(n);
for(int i = 0; i < n - 1; i++){
int a, b; cin >> a >> b; a--, b--;
g[a].pb(b); g[b].pb(a);
}
string s;
cin >> s;
vector<int> bos(n);
vector<int> dolu(n);
function<void(int, int)> dfs = [&](int u, int p){
for(int v : g[u]){
if(v == p) continue;
dfs(v, u);
}
if(s[u] == '0'){
int mxbos = 0;
int herdolu = 0;
for(int v : g[u]){
if(v == p) continue;
mxbos = max(mxbos, bos[v]);
herdolu += dolu[v];
}
bos[u] = max(bos[u], mxbos);
bos[u] = max(bos[u], herdolu);
dolu[u] = max(dolu[u], herdolu);
}
else{
int mxdolu = 0;
int mxbos = 0;
int herdolu = 0;
for(int v : g[u]){
if(v == p) continue;
mxdolu = max(mxdolu, dolu[v]);
mxbos = max(mxbos, bos[v]);
herdolu += dolu[v];
}
bos[u] = max(bos[u], mxdolu + 1);
bos[u] = max(bos[u], herdolu - 1);
bos[u] = max(bos[u], 1);
bos[u] = max(bos[u], mxbos);
dolu[u] = max(dolu[u], 1);
dolu[u] = max(dolu[u], herdolu - 1);
}
};
dfs(0, 0);
cout << bos[0] << endl;
}
