// Starcraft 2 enjoyer //
#include <bits/stdc++.h>
// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
using namespace std;
#define LSOne(X) ((X) & -(X))
const int N = 3e5 + 5;
const int K = 1e2 + 5;
const int LG = 20;
const int INF = 1e9 + 5;
const int B = 1000;
const int MOD = 1e9 + 7;
int n, dp[N], ans;
string s;
vector<int> adj[N];
void dfs(int c, int p)
{
int mx = 0;
for (int i : adj[c])
{
if (i == p)
continue;
dfs(i, c);
if (s[c] == '1')
ans = max(ans, dp[i] + 1);
mx += dp[i];
}
if (s[c] == '1')
{
dp[c] = 1;
mx--;
}
dp[c] = max(mx, dp[c]);
ans = max(ans, dp[c]);
// cout << dp[c] << " " << ans << " " << c << "\n";
}
inline void solve()
{
cin >> n;
ans = 0;
for (int x = 0; x < n - 1; x++)
{
int a, b;
cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
cin >> s;
s = '0' + s;
// for (int x = 1; x <= n; x++)
// {
// if (s[x] == '1')
// cout << x << " ";
// }
// cout << "\n";
dfs(1, 0);
cout << ans << "\n";
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
for (int x = 1; x <= t; x++)
{
solve();
}
return 0;
}
