#include <bits/stdc++.h>
using namespace std;
int morh[100001], parent[100001], pos[100001], temp = 0, ans = 0;
int calculate(int i) {
  int posi = i, ans = 0;
  while (posi != 0) {
    if (pos[posi] > 1)
      break;
    else {
      posi = parent[posi];
      ans++;
    }
  }
  return ans;
}
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &morh[i]);
  }
  for (int i = 1; i <= n; i++) {
    scanf("%d", &parent[i]);
    pos[parent[i]]++;
  }
  int temp2;
  for (int i = 1; i <= n; i++) {
    if (morh[i] == 1) {
      temp2 = calculate(i);
      if (temp2 > ans) {
        ans = temp2;
        temp = i;
      }
    }
  }
  temp2 = ans;
  int give_ans[ans], i = 0;
  for (int j = 0; j < temp2; j++) {
    give_ans[i] = temp;
    i++;
    temp = parent[temp];
  }
  printf("%d\n", ans);
  for (int i = ans - 1; i >= 0; i--) printf("%d ", give_ans[i]);
  printf("\n");
}
