#include <bits/stdc++.h>
using namespace std;
const int INF = INT_MAX;
const long long limit = 1LL * 1e18;
const int MOD = 1e9 + 711;
const int MOD2 = 1e9 + 933;
const int mod = 1e9 + 7;
const int maxn = 5e5 + 10;
signed main() {
  cout.tie(0);
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  int m, k, n, s, got = 0, r = 0;
  cin >> m >> k >> n >> s;
  set<int> d;
  vector<int> have(maxn), req(maxn), a(m + 1);
  for (int i = 1; i <= m; ++i) cin >> a[i];
  for (int i = 0; i < s; ++i) {
    int x;
    cin >> x;
    req[x]++;
    d.emplace(x);
  }
  vector<int> ans;
  bool ok = false;
  for (int l = 1; l <= m; ++l) {
    if (d.find(a[l]) == d.end()) continue;
    if (l > r && ++have[a[l]] == req[a[l]]) got += req[a[l]];
    r = max(l, r);
    while (r < m && got < s) {
      ++r;
      if (d.find(a[r]) != d.end()) {
        if (++have[a[r]] == req[a[r]]) got += req[a[r]];
      }
    }
    if (got == s && l / k == r / k) {
      ok = true;
      break;
    }
    if (got == s && ((l - 1 - ((l - 1) % k) + m - r) / k >= n - 1)) {
      int len = r - l + 1;
      ok = true;
      for (int i = l - 1; i % k; --i) ans.push_back(i);
      for (int i = l; i <= r && len > k; ++i) {
        if (d.find(a[i]) == d.end()) {
          --len;
          ans.push_back(i);
        } else if (have[a[i]] > req[a[i]]) {
          --have[a[i]];
          --len;
          ans.push_back(i);
        }
      }
      break;
    }
    if (have[a[l]]-- == req[a[l]]) got -= req[a[l]];
  }
  if (!ok) {
    cout << -1;
  } else {
    cout << ans.size() << '\n';
    for (auto &i : ans) cout << i << ' ';
  }
  return 0;
}
