#include <bits/stdc++.h>
using namespace std;
int dx[] = {0, 1, -1, 0};
int dy[] = {1, 0, 0, -1};
long double PI = 3.14159265358979323846264338327950;
pair<int, int> p[12000002];
int a[12000002], b[12000002];
int m, n, k;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> m >> k;
  for (int i = 1, x; i <= n; i++) {
    cin >> x;
    a[x]++;
    if (a[x] > k) {
      cout << -1;
      return 0;
    }
  }
  for (int i = 1, x; i <= m; i++) {
    cin >> x;
    p[i] = {x, i};
  }
  sort(p + 1, p + 1 + m);
  int ch = 0;
  int res = 0;
  for (int i = 1; i <= m; i++) {
    for (; a[ch] == k; ch++)
      ;
    if (ch > p[i].first)
      continue;
    else {
      res++;
      b[res] = p[i].second, a[ch]++;
    }
  }
  cout << res << "\n";
  for (int i = 1; i <= res; i++) cout << b[i] << " ";
  return 0;
}
