#include <bits/stdc++.h>
#define _ ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define fore(i,a,b) for(lli i = (a), abcdxd = (b); i < abcdxd; i++)
#define f first
#define s second
#define pb push_back
#define ENDL '\n'
#define sz(s) lli((s).size())
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
using namespace std;
typedef int lli;
typedef pair<lli,lli> ii;
typedef vector<lli> vi;
typedef vector<ii> vii;
typedef long double ld;
#define deb(x) cout << #x << ": " << x << endl;
const lli N = 2e5 + 12;
lli n;
vii adj[N];
bool pw[N];
lli dp[N+N];
bool vis[N+N];
lli calc(lli u, lli p, lli id){
lli& ans = dp[id];
bool& mem = vis[id];
if (!mem){
mem = true;
ans = 0;
for (auto i : adj[u]) if (i.f != p) ans += calc(i.f, u, i.s);
ans = max(lli(pw[u]), ans - pw[u]);
}
return ans;
}
lli f(lli u){
lli ans = 1, sum = -1;
for (auto i : adj[u]){
lli xx = calc(i.f, u, i.s);
sum += xx;
ans = max(ans, xx + 1);
}
return max(ans, sum - 1);
}
void solve(){
cin >> n;
fore(i,0,n-1){
lli a, b; cin >> a >> b; a--, b--;
adj[a].pb({b, i+i});
adj[b].pb({a, i+i+1});
}
fore(i,0,n){
char c; cin >> c;
pw[i] = (c == '1');
}
lli ans = 0;
fore(i,0,n) if (pw[i]) ans = max(ans, f(i));
cout << ans << ENDL;
}
int main(){ // _
// freopen("tracing.in", "r", stdin);
// freopen("tracing.out", "w", stdout);
// lli t; cin >> t;
// while (t--)
solve();
return 0;
}
