#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MAXN = 2e5;
vector<int> adj[MAXN];
bitset<MAXN> hasPower;
int dp[MAXN][2]; // DP[curNode][onBefore]
int nbSommets;
void dfs(int u, int p) {
for (int v : adj[u])
if (v != p)
dfs(v, u);
// Put power :
if (hasPower[u]) {
dp[u][0] = 1;
for (int v : adj[u])
if (v != p)
dp[u][0] = max(dp[u][0], 1 + dp[v][1]);
dp[u][1] = 1;
}
// Don't put power :
// Put power in only one place :
for (int v : adj[u])
if (v != p) {
for (int b = 0; b < 2; ++b)
dp[u][b] = max(dp[u][b], dp[v][b] - (b and hasPower[u]));
}
// Or put power in multiple places :
int tot = 0;
for (int v : adj[u])
if (v != p)
tot += dp[v][1];
dp[u][0] = max(dp[u][0], tot - hasPower[u]);
dp[u][1] = max(dp[u][1], tot - hasPower[u]);
}
signed main(void) {
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> nbSommets;
for (int i = 1; i < nbSommets; ++i) {
int u, v;
cin >> u >> v;
--u, --v;
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int i = 0; i < nbSommets; ++i) {
char c;
cin >> c;
hasPower[i] = c == '1';
}
dfs(0, 0);
cout << dp[0][0] << endl;
}
