#include <bits/stdc++.h>
using namespace std;
int Max(int a, int b) { return (((b - a) >> (32 - 1)) & (a ^ b)) ^ b; }
int Min(int a, int b) { return (((b - a) >> (32 - 1)) & (a ^ b)) ^ a; }
long long GCD(long long a, long long b) { return b != 0 ? GCD(b, a % b) : a; }
long long LCM(long long a, long long b) { return a * (b / GCD(a, b)); }
long long Pow(long long n, long long e) {
  if (e == 0) return 1;
  if (e == 1)
    return n;
  else if (e & 1) {
    long long t = Pow(n, e / 2);
    return n * t * t;
  } else {
    long long t = Pow(n, e / 2);
    return t * t;
  }
}
const int MAX = 100005;
int t[MAX];
vector<int> edge[MAX];
int dp[MAX], nextt[MAX];
bool vis[MAX];
int DFS(int id) {
  if (t[id] == 1) return 1;
  if (vis[id]) return -100000000;
  if (dp[id] != -1) return dp[id];
  vis[id] = true;
  int res = -100000000, m = 0;
  for (int i = 0, max_ = ((int)(edge[id]).size()); i < max_; ++i) {
    int nid = edge[id][i];
    if (t[nid] == 0) ++m;
    int r = 1 + DFS(nid);
    if (r > res) {
      res = r;
      nextt[id] = nid;
    }
  }
  if ((int)(edge[id]).size() > 1)
    return dp[id] = -100000000;
  else
    return dp[id] = res;
}
void Print(int id) {
  printf("%d ", id + 1);
  if (nextt[id] >= 0) Print(nextt[id]);
}
int main() {
  int N;
  scanf("%d", &N);
  for (int i = 0, max_ = (N); i < max_; ++i) scanf("%d", &t[i]);
  for (int i = 0, max_ = (N); i < max_; ++i) {
    int a;
    scanf("%d", &a);
    if (a > 0) {
      --a;
      edge[a].push_back(i);
    }
  }
  memset(dp, -1, sizeof(dp));
  ;
  memset(nextt, -1, sizeof(nextt));
  ;
  int res = 0, resID = -1;
  for (int i = 0, max_ = (N); i < max_; ++i) {
    memset(vis, false, sizeof(vis));
    ;
    int r = DFS(i);
    if (r > res) {
      res = r;
      resID = i;
    }
  }
  printf("%d\n", res);
  Print(resID);
  return 0;
}
