#include <bits/stdc++.h>
using namespace std;
template <typename T>
bool vmin(T& a, T b) {
  return (a > b) ? (a = b, true) : (false);
}
template <typename T>
bool vmax(T& a, T b) {
  return (a < b) ? (a = b, true) : (false);
}
template <typename T>
T smax(T x) {
  return x;
}
template <typename T, typename... K>
T smax(T a, const K&... args) {
  return max(a, smax(args...));
}
template <typename T>
T smin(T x) {
  return x;
}
template <typename T, typename... K>
T smin(T a, const K&... args) {
  return min(a, smin(args...));
}
template <typename A, typename B>
ostream& operator<<(ostream& os, const pair<A, B>& z) {
  os << "(" << z.first << ", " << z.second << ')';
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& a) {
  bool isfirst = true;
  os << "{";
  for (auto z : a) {
    if (!isfirst) {
      os << ", ";
    }
    os << z;
    isfirst = false;
  }
  os << '}';
  return os;
}
const int inf = (signed)(~0u >> 2);
const long long llf = (signed long long)(~0ull >> 2);
template <typename T>
void discrete(T* a, int* b, int n) {
  vector<T> v(a + 1, a + n + 1);
  sort(v.begin(), v.end());
  for (int i = 1; i <= n; i++)
    b[i] = lower_bound(v.begin(), v.end(), a[i]) - v.begin() + 1;
}
const int N = 5e5 + 5;
int m, n, k, s;
int a[N], b[N];
int main() {
  scanf("%d%d%d%d", &m, &k, &n, &s);
  for (int i = 1; i <= m; i++) {
    scanf("%d", a + i);
  }
  int rest = 0;
  for (int i = 1, x; i <= s; i++) {
    scanf("%d", &x);
    rest += !b[x];
    b[x]++;
  }
  auto mdf = [&](int idx, int dlt) {
    rest -= b[idx] > 0;
    b[idx] += dlt;
    rest += b[idx] > 0;
  };
  for (int l = 1, r = 1; l + k - 1 <= m; mdf(a[l++], 1)) {
    while (r <= m && rest) {
      mdf(a[r++], -1);
    }
    if (rest) break;
    if (m - ((l - 1) % k) - max(r - l - k, 0) >= n * k) {
      for (int i = l; i < r; i++) mdf(a[i], 1);
      int other = k - s, put = 0;
      vector<int> S;
      for (int i = 0; i < ((l - 1) % k); i++) S.push_back(i + 1);
      for (int i = l; i <= m && put < k; i++) {
        if (b[a[i]]) {
          --b[a[i]];
          put++;
        } else if (other) {
          put++;
          other--;
        } else {
          S.push_back(i);
        }
      }
      printf("%d\n", (signed)S.size());
      for (auto e : S) printf("%d ", e);
      return 0;
    }
  }
  puts("-1");
  return 0;
}
