#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
using vll = vector<ll>;
using pll = pair<ll,ll>;
#define pb push_back
#define MP make_pair
#define f first
#define s second
#define mid ((l+r)>>1)
#define SZ(x) (int)(x.size())
#define MP make_pair
#define all(x) x.begin(), x.end()
const ll MAXN = 2e5 + 5;
const ll MOD = 998244353;
const ll INF = 1e16;
ll N, ans;
string S;
vll g[MAXN];
ll dp[MAXN], dp2[MAXN];
void solve(ll nodo, ll p) {
if (S[nodo - 1] == '1') { dp2[nodo] = 1; dp[nodo] = -1; }
else { dp[nodo] = dp2[nodo] = 0; }
for (auto &it : g[nodo]) {
if (it == p) continue;
solve(it, nodo);
dp2[nodo] = max(dp2[nodo], dp2[it]);
dp[nodo] = max(dp[nodo], dp[nodo] + dp[it]);
}
if (S[nodo - 1] == '1') dp[nodo] = max(dp[nodo], 1LL);
else dp[nodo] = max(dp[nodo], 0LL);
dp2[nodo] = max(dp2[nodo], dp[nodo]);
}
void dfs(ll nodo, ll p) {
if (nodo == p) solve(nodo, p);
else {
// recalcula del padre
ll aux = -1;
dp[p] = 1;
for (auto &it : g[p]) {
if (it == nodo) continue;
dp[p] = max(dp[it], dp[p]);
aux += dp[it];
}
dp[p] = max(dp[p], aux);
// recalcula del nodo
aux = -1;
dp[nodo] = 1;
for (auto &it : g[nodo]) {
dp[nodo] = max(dp[it], dp[nodo]);
aux += dp[it];
}
dp[nodo] = max(dp[nodo], aux);
}
ans = max(ans, dp[nodo]);
for (auto &it : g[nodo]) {
if (it == p) continue;
dfs(it, nodo);
}
}
void tc() {
cin >> N;
for (int i = 0; i < N - 1; i++) {
ll a, b; cin >> a >> b;
g[a].pb(b);
g[b].pb(a);
}
cin >> S;
//dfs(1, 1);
for (int i = 1; i <= N; i++) {
solve(i, i);
ans = max(ans, dp2[i]);
}
cout << ans << "\n";
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
int t = 1; //cin >> t;
while (t--) tc();
return 0;
}
