#include <bits/stdc++.h>
#define X first
#define Y second
#define pb push_back
#define pii pair<int, int>
typedef long long ll;
using namespace std;
const int MOD = 1e9 + 7;
const ll INF = 1e18;
const int OFF = (1 << 20);
int n, a, b, sol = 0;
char c;
vector<int> v[200005];
int val[200005];
int rek(int x, int prt) {
int tren = 0, koldj = 0;
for (int i = 0; i < (int)v[x].size(); i++) {
if (prt == v[x][i]) continue;
int sad = rek(v[x][i], x);
tren += sad;
if (sad > 0) koldj++;
}
if (val[x] == 0) {
sol = max(sol, tren);
return tren;
}
else {
if (koldj > 1) sol = max(sol, tren-1);
else sol = max(sol, tren+1);
return max(tren-1, 1);
}
}
int main () {
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n;
for (int i = 0; i < n-1; i++) {
cin >> a >> b;
v[a].push_back(b);
v[b].push_back(a);
}
for (int i = 1; i <= n; i++) {
cin >> c;
val[i] = c - '0';
}
rek(1, 0);
cout << sol;
return 0;
}
