#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<stack<int> > vs;
  int maxi = -1, maximum = 0, nbVertices, n, type[100009], destination[100009],
      source[100009];
  cin >> n;
  vs = vector<stack<int> >(n);
  for (int i = 0; i < n; ++i) {
    source[i] = 0;
  }
  for (int i = 0; i < n; ++i) {
    cin >> type[i];
  }
  for (int i = 0; i < n; ++i) {
    cin >> destination[i];
    destination[i] -= 1;
    if (destination[i] != -1) source[destination[i]]++;
  }
  for (int i = 0; i < n; ++i) {
    if (type[i]) {
      int j = i;
      nbVertices = 1;
      while (source[destination[j]] == 1 && destination[j] != -1) {
        ++nbVertices;
        vs[i].push(j + 1);
        j = destination[j];
      }
      vs[i].push(j + 1);
      if (maximum < nbVertices) {
        maximum = nbVertices;
        maxi = i;
      }
    }
  }
  cout << maximum << endl;
  while (vs[maxi].size()) {
    int top = vs[maxi].top();
    cout << top << ' ';
    vs[maxi].pop();
  }
  cout << endl;
  return 0;
}
