#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
using vint = vector<int>;
using vll = vector<ll>;
using vld = vector<ld>;
using vpii = vector<pii>;
using vpil = vector<pil>;
using vpli = vector<pli>;
using vpll = vector<pll>;
#define x first
#define y second
#define all(v) v.begin(),v.end()
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<vint> e(n + 1);
for(int i = 0; i < n - 1; i++) {
int x, y;
cin >> x >> y;
e[x].push_back(y);
e[y].push_back(x);
}
string s;
cin >> s;
vint a(n + 1);
for(int i = 0; i < n; i++) a[i + 1] = (s[i] == '1');
vint d(n + 1), tot(n + 1);
function<int(int, int)> f = [&](int x, int y) {
for(int i : e[x]) {
if(i == y) continue;
int t = f(i, x);
tot[x] += t;
}
return d[x] = max(tot[x] - a[x], a[x]);
};
f(1, 0);
int ans = min(2, int(count(all(a), 1)));
function<void(int, int)> g = [&](int x, int y) {
ans = max(ans, d[x]);
for(int i : e[x]) {
if(i == y) continue;
int dx = d[x], di = d[i], tx = tot[x], ti = tot[i];
tot[x] -= d[i];
d[x] = max(tot[x] - a[x], a[x]);
tot[i] += d[x];
d[i] = max(tot[i] - a[i], a[i]);
g(i, x);
d[x] = dx; d[i] = di; tot[x] = tx; tot[i] = ti;
}
};
g(1, 0);
cout << ans << '\n';
return 0;
}
