#include <bits/stdc++.h>
using namespace std;
const int sz = 1500000;
const long long MAX = 10000000000000000;
template <typename T>
T abs(T a) {
  return a < 0 ? -a : a;
}
const long long MOD = 1e9 + 7;
const long long MASK = 1099511627776LL;
int napr[8][2] = {{0, 1}, {1, 0},  {-1, 0}, {0, -1},
                  {1, 1}, {1, -1}, {-1, 1}, {-1, -1}};
const int PRIME = 4999999;
vector<long long> v;
vector<long double> b(401, -1);
vector<char> used(401, false);
int gcd(int a, int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int len;
bool comparer(pair<pair<int, int>, int> a, pair<pair<int, int>, int> b) {
  if (a.first.first / len == b.first.first / len) {
    return a.first.second < b.first.second;
  }
  return a.first.first < b.first.first;
}
long long poww(long long a, long long step) {
  if (step == 0) {
    return 1;
  }
  if (step % 2) {
    return (a * poww(a, step - 1) % (int)(1e9 + 7));
  } else {
    long long buf = poww(a, step / 2);
    return (buf * buf) % (int)(1e9 + 7);
  }
}
vector<int> fenvik;
int n;
int maxV = -1;
vector<int> isOt;
vector<vector<int> > g, rg;
vector<int> flag;
vector<int> ts;
vector<int> path;
bool isOtv = true;
void dfs(int v, int len = 0) {
  flag[v] = 1;
  if (len > maxV) {
    maxV = max(len, maxV);
    path.clear();
    isOtv = false;
  }
  for (long long i = 0; i < g[v].size(); i++) {
    if (!flag[g[v][i]]) dfs(g[v][i], len + 1);
  }
  if (!isOtv) {
    path.push_back(v);
  }
}
int main() {
  int n;
  cin >> n;
  isOt.resize(n);
  g.resize(n);
  vector<int> start;
  flag.resize(n, 0);
  vector<int> otel;
  for (long long i = 0; i < n; i++) {
    cin >> isOt[i];
    if (isOt[i]) {
      otel.push_back(i);
    }
  }
  vector<int> cp(n, 0);
  for (long long i = 0; i < n; i++) {
    int buf;
    cin >> buf;
    if (buf) {
      buf--;
      cp[buf]++;
      if (cp[buf] > 1) flag[buf] = 1;
      g[i].push_back(buf);
    } else {
      start.push_back(i);
    }
  }
  flag.resize(n, 0);
  vector<int> res;
  for (long long i = 0; i < otel.size(); i++) {
    isOtv = true;
    path.clear();
    int oldV = maxV;
    dfs(otel[i]);
    if (oldV < maxV) {
      res = path;
      oldV = maxV;
    }
  }
  cout << res.size() << endl;
  for (long long i = 0; i < res.size(); i++) {
    cout << res[i] + 1 << ' ';
  }
  return 0;
}
