#include <bits/stdc++.h>
using namespace std;
const long long maxn = 1e6 + 500;
vector<long long> vec;
vector<long long> vrt;
vector<pair<long long, long long> > vs;
long long u[maxn];
long long k;
long long p1, p2;
char next(long long a) {
  long long mo = 0;
  while (p1 < vec.size() && p2 < vrt.size()) {
    if (vec[p1] < vrt[p2]) {
      if (vec[p1] < a) return 0;
      p1++;
    } else {
      if (vrt[p2] < a) return 0;
      p2++;
    }
    mo++;
    if (mo == k) return 1;
  }
  while (p1 < vec.size()) {
    if (vec[p1] < a) return 0;
    mo++;
    p1++;
    if (mo == k) return 1;
  }
  while (p2 < vrt.size()) {
    if (vrt[p2] < a) return 0;
    mo++;
    p2++;
    if (mo == k) return 1;
  }
  return 2;
}
bool good(long long a) {
  p1 = 0;
  p2 = vrt.size() - a;
  long long roz = 0, u;
  while (1) {
    u = next(roz);
    roz++;
    if (u == 0) return 0;
    if (u == 2) return 1;
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, m, v;
  cin >> n >> m >> k;
  for (long long i = 0; i < n; i++) {
    cin >> v;
    vec.push_back(v);
  }
  for (long long i = 0; i < m; i++) {
    cin >> v;
    u[i] = v;
    vrt.push_back(v);
    vs.push_back(make_pair(v, i));
  }
  sort(vec.begin(), vec.end());
  sort(vrt.begin(), vrt.end());
  sort(vs.begin(), vs.end());
  if (!good(0)) {
    cout << -1;
    return 0;
  }
  long long s = 0;
  long long t = m + 1;
  while (t - s > 1) {
    long long mm = (t + s) / 2;
    if (good(mm)) {
      s = mm;
    } else {
      t = mm;
    }
  }
  cout << s << endl;
  for (long long i = m - 1; i >= m - s; i--) {
    cout << vs[i].second + 1 << ' ';
  }
}
