#include <bits/stdc++.h>
using namespace std;
int n, dp[300005], k = 0, b[300005];
vector<int> ke[300005];
void dfs(int u, int par) {
  if (ke[u].size() == 1 && u != 1) {
    dp[u] = 1;
    k++;
    return;
  }
  if (b[u])
    dp[u] = 1e9;
  else
    dp[u] = 0;
  for (int v : ke[u])
    if (v != par) {
      dfs(v, u);
      if (b[u])
        dp[u] = min(dp[u], dp[v]);
      else
        dp[u] += dp[v];
    }
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie();
  cout.tie();
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> b[i];
  int u;
  for (int i = 2; i <= n; i++) {
    cin >> u;
    ke[u].push_back(i);
    ke[i].push_back(u);
  }
  dfs(1, 0);
  cout << k - dp[1] + 1;
  return 0;
}
