#include <bits/stdc++.h>
using namespace std;
int N, K, M, S;
int arr[500000];
int raito[500005];
int seen[500005];
int bucket[500005];
int shift[500005];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> M >> K >> N >> S;
  for (int i = 0; i < M; i++) {
    cin >> arr[i];
  }
  int t;
  for (int i = 0; i < S; i++) {
    cin >> t;
    bucket[t]++;
  }
  for (int i = 0; i < 500005; i++) seen[i] = -1;
  for (int i = M - 1; i >= 0; i--) {
    raito[i] = seen[arr[i]];
    seen[arr[i]] = i;
  }
  int maxima = 0;
  for (int i = 0; i < 500005; i++) {
    if (bucket[i] == 0) continue;
    int cur = seen[i];
    int p = 1;
    while (cur != -1 && p < bucket[i]) {
      cur = raito[cur];
      p++;
    }
    if (cur == -1) {
      cout << -1;
      return 0;
    }
    shift[i] = cur;
    maxima = max(maxima, cur);
  }
  vector<int> adj;
  for (int i = 0; i < M;) {
    int total = i / K + 1 + ((M - 1) - (maxima + 1) + 1) / K;
    if (total >= N) {
      int extra = K - S;
      for (int j = i; j <= maxima; j++) {
        if (extra <= 0 && bucket[arr[j]] == 0) {
          adj.push_back(j + 1);
        } else if (bucket[arr[j]] == 0) {
          extra--;
        } else {
          bucket[arr[j]]--;
        }
      }
      cout << adj.size() << "\n";
      for (int j = 0; j < adj.size(); j++) {
        cout << adj[j] << " ";
      }
      return 0;
    }
    if (i + 1 == M) break;
    int pp = 0;
    if (bucket[arr[i]] != 0) {
      shift[arr[i]] = raito[shift[arr[i]]];
      maxima = max(maxima, shift[arr[i]]);
      if (shift[arr[i]] == -1) {
        cout << -1;
        return 0;
      }
    }
    i++;
  }
  cout << -1;
  return 0;
}
