#include <bits/stdc++.h>
using namespace std;
using ii = pair<int, int>;
using ll = long long;
using vi = vector<int>;
template <typename T>
using minheap = priority_queue<T, vector<T>, greater<T>>;
template <typename T>
using maxheap = priority_queue<T>;
template <typename T>
ostream& operator<<(ostream& os, vector<T> v) {
  os << "[ ";
  for (auto e : v) os << e << " ";
  return os << "]";
}
template <typename T, typename V>
ostream& operator<<(ostream& os, set<T, V> v) {
  os << "{ ";
  for (auto e : v) os << e << " ";
  return os << "}";
}
template <typename T, typename V, typename S>
ostream& operator<<(ostream& os, map<T, V, S> v) {
  os << "{ ";
  for (auto e : v) os << e << " ";
  return os << "}";
}
template <typename T, typename V>
ostream& operator<<(ostream& os, pair<T, V> x) {
  return os << "( " << x.first << ", " << x.second << " )";
}
template <typename T>
istream& operator>>(istream& is, vector<T>& v) {
  for (auto& e : v) is >> e;
  return is;
}
template <typename T, typename V>
istream& operator>>(istream& is, pair<T, V>& x) {
  return is >> x.first >> x.second;
}
void solve();
int main() { solve(); }
const int MAX = 3e5 + 5;
int n, type[MAX], p[MAX], dp[MAX], numch[MAX], numleaves[MAX];
void solve() {
  scanf("%d", &n);
  for (int i = 1; i <= n; ++i) scanf("%d", &type[i]);
  for (int i = 2; i <= n; ++i) {
    scanf("%d", &p[i]);
    ++numch[p[i]];
  }
  for (int i = n; i; --i) {
    if (numch[i] == 0) {
      numleaves[i] = 1;
    }
    numleaves[p[i]] += numleaves[i];
  }
  for (int u = n; u; --u) {
    if (numch[u] == 0) {
      dp[u] = 1;
    } else if (type[u] == 0) {
      dp[u] = numleaves[u] - dp[u] + 1;
    }
    if (type[p[u]] == 1) {
      dp[p[u]] = max(dp[p[u]], numleaves[p[u]] - numleaves[u] + dp[u]);
    } else {
      dp[p[u]] += numleaves[u] - dp[u] + 1;
    }
  }
  printf("%d\n", dp[1]);
}
