#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define ar array
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
const int maxn = 2e5 + 5;
int N, f[maxn];
vector<int> adj[maxn];
bool mark[maxn];
signed main(void)
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#ifdef LOCAL
freopen("A.INP", "r", stdin);
freopen("A.OUT", "w", stdout);
#endif // LOCAL
cin >> N;
for (int i = 1; i < N; ++i){
int u, v; cin >> u >> v;
adj[u].eb(v); adj[v].eb(u);
}
for (int i = 1; i <= N; ++i){
char c; cin >> c;
c -= '0'; mark[i] = c;
}
int res = 0;
function<void(int, int)> dfs = [&](int u, int par)
{
int mx = 0;
for (int v : adj[u]){
if (v != par){
dfs(v, u);
f[u] += f[v];
mx = max(mx, f[v] + 1);
}
}
if(mark[u]){
res = max(res, mx);
f[u]--;
f[u] = max(f[u], 1);
}
res = max(res, f[u]);
};
dfs(1, -1);
cout << res;
}
