// Born_To_Laugh - Hughie Do
#include <bits/stdc++.h>
#define alle(AC) AC.begin(), AC.end()
#define fi first
#define se second
using namespace std;
typedef long long ll;
[[maybe_unused]] const int MOD = 998244353, INF = 1e9 + 7;
const int maxn = 2e5 + 10;
int n, ans;
int dp[maxn];
vector<int> adj[maxn];
string s;
void dfs(int a, int par){
int sum = 0;
for(auto &elm: adj[a]){
if(elm == par) continue;
dfs(elm, a);
sum += dp[elm];
if(s[a] == '1'){
ans = max(ans, dp[elm] + 1);
}
}
if(s[a] == '1'){
dp[a] = max(1, sum - 1);
}
else{
dp[a] = sum;
}
ans = max(ans, dp[a]);
}
void solve(){
cin >> n;
for(int i=1; i<n; ++i){
int a, b;cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
cin >> s; s = "$" + s;
dfs(1, -1);
cout << ans << '\n';
}
signed main(){
// freopen("inp.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
solve();
}
