#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
void sc(int &x) {
  register int c = getchar();
  x = 0;
  int neg = 0;
  for (; ((c < 48 || c > 57) && c != '-'); c = getchar())
    ;
  if (c == '-') {
    neg = 1;
    c = getchar();
  }
  for (; c > 47 && c < 58; c = getchar()) {
    x = (x << 1) + (x << 3) + c - 48;
  }
  if (neg) x = -x;
}
long long power(long long a, long long b, long long mod) {
  long long res = 1;
  while (b > 0) {
    if (b % 2 != 0) res = (res * a) % mod;
    a = (a * a) % mod;
    b /= 2;
  }
  return res;
}
long long gcd(long long a, long long b) {
  return ((b == 0) ? a : gcd(b, a % b));
}
pair<int, int> dum[2000010], f[1000005], s[1000005];
int store[2000005];
int main() {
  int i, tot, j, n, m, low, l1, l2, high, cnt, ans, mid, k, test;
  sc(n);
  sc(m);
  sc(k);
  for (i = 1; i < n + 1; i++) {
    sc(f[i].first);
    f[i].second = i;
  }
  for (i = 1; i < m + 1; i++) {
    sc(s[i].first);
    s[i].second = i;
  }
  sort(f + 1, f + n + 1);
  cnt = 1;
  for (i = 1; i < n + 1; i++) {
    if (f[i].first < cnt - 1) {
      printf("-1\n");
      return 0;
    }
    if (i == cnt * k) cnt++;
  }
  sort(s + 1, s + m + 1);
  low = 0;
  high = m;
  while (low <= high) {
    mid = (low + high) / 2;
    l1 = 1;
    l2 = m - mid + 1;
    tot = 1;
    while (tot <= n + mid) {
      while ((l2 == m + 1) || (l1 <= n && l2 <= m && tot <= n + mid &&
                               f[l1].first <= s[l2].first)) {
        if (l1 == n + 1) break;
        dum[tot].first = f[l1++].first;
        dum[tot++].second = -1;
      }
      while ((l1 == n + 1) || (l1 <= n && l2 <= m && tot <= n + mid &&
                               f[l1].first > s[l2].first)) {
        if (l2 == m + 1) break;
        dum[tot].first = s[l2].first;
        dum[tot++].second = s[l2++].second;
      }
    }
    cnt = 1;
    for (i = 1; i < n + mid + 1; i++) {
      if (dum[i].first < cnt - 1) {
        break;
      }
      if (i == cnt * k) cnt++;
    }
    if (i < n + mid + 1)
      high = mid - 1;
    else {
      low = mid + 1;
      ans = mid;
      cnt = 1;
      for (i = 1; i < mid + 1; i++) {
        while (dum[cnt].second == -1) cnt++;
        store[i] = dum[cnt++].second;
      }
    }
  }
  printf("%d\n", ans);
  for (i = 1; i < ans + 1; i++) printf("%d ", store[i]);
  return 0;
}
