#include<bits/stdc++.h>
using namespace std;
const int MAXN = 2e5 + 5;
int n;
vector<int> adj[MAXN];
int cur = 0;
int dp[MAXN];
string s;
int ans = 0;
void dfs(int u, int par)
{
int total = 0;
int maxx = 0;
for (int v : adj[u])
{
if (v == par)
{
continue;
}
dfs(v, u);
total += dp[v];
maxx = max(maxx, dp[v]);
}
if (s[u - 1] == '1')
{
ans = max({ans, total - 1, maxx + 1});
}
else
{
ans = max(ans, total);
}
int cur = 0;
if (s[u - 1] == '1')
{
cur = 1;
}
dp[u] = max(cur, total - cur);
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n;
for (int i = 1; i < n; i++)
{
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
cin >> s;
dfs(1, 0);
cout << ans;
}
