#include <bits/stdc++.h>
using namespace std;
const int N = 1 << 20, M = 1 << 10;
const int mod = 1e9 + 7;
const long long P = 7 * 17 << 23 | 1, G = 3;
vector<int> a(N), b(N), cnt(N), t(N);
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0), cout.tie(0);
  int n, m, k, s;
  cin >> m >> k >> n >> s;
  for (int i = 0; i < m; i++) cin >> a[i];
  int tc = 0;
  for (int i = 0; i < s; i++) {
    cin >> b[i];
    if (!cnt[b[i]]++) tc++;
  }
  int l = 0, r = 0, c = 0;
  vector<int> ans;
  while (1) {
    if (c < tc) {
      if (r == m) break;
      ++t[a[r]];
      if (cnt[a[r]] && t[a[r]] == cnt[a[r]]) c++;
      r++;
    } else {
      while (c == tc) {
        --t[a[l]];
        if (cnt[a[l]] && t[a[l]] < cnt[a[l]]) {
          c--;
          int w = r - l;
          int ss = w - k, ww = l % k;
          ;
          int tt = ss + ww;
          if (tt < 0) return cout << 0 << endl, 0;
          if (m - tt >= n * k) {
            ++t[a[l]];
            if (ss < 0) ww += ss, ss = 0;
            for (int i = 0; i < ww; i++) ans.push_back(i + 1);
            for (int i = l; i < r && ss; i++)
              if (!cnt[a[i]] || cnt[a[i]] < t[a[i]])
                ans.push_back(i + 1), t[a[i]]--, ss--;
            cout << ans.size() << endl;
            for (int &e : ans) cout << e << ' ';
            cout << endl;
            return 0;
          }
        }
        l++;
      }
    }
  }
  cout << -1 << endl;
  return 0;
}
