// #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx")
// #pragma comment(linker, "/stack:200000000"]

#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <unordered_set>
#include <unordered_map>
#include <set>
#include <map>
#include <queue>
#include <deque>
#include <bitset>
#include <stack>
#include <random>
#include <fstream>
#include <sstream>
#include <chrono>

#define fi first
#define se second
#define pb push_back
#define ll long long
#define ld long double
#define hm unordered_map
#define pii pair<int, int>
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define cinv(v) for (auto& x: v) cin >> x
#define fr(i, n) for (int i = 0; i < n; ++i)
#define fl(i, l, n) for (int i = l; i < n; ++i)

#define int ll

template <typename T1, typename T2> inline bool chkmin(T1 &x, const T2 &y) {if (x > y) {x = y; return 1;} return 0;}
template <typename T1, typename T2> inline bool chkmax(T1 &x, const T2 &y) {if (x < y) {x = y; return 1;} return 0;}

using namespace std;

#ifdef __LOCAL
	#define dbg(x) cerr << #x << " : " << x << '\n'
	const int maxn = 20;
#else
	#define dbg(x)
	const int maxn = 2e5 + 20;
#endif

//tg: @galebickosikasa

ostream& operator << (ostream& out, vector<int>& v) {
	for (auto& x: v) out << x << ' ';
	return out;
}

ostream& operator << (ostream& out, pii& v) {
	out << v.fi << ", " << v.se;
	return out;
}

istream& operator >> (istream& in, pii& a) {
	in >> a.fi >> a.se;
	return in;
}

const ll inf = (ll) 2e9;
const ld pi = asin (1) * 2;
const ld eps = 1e-8;
const ll mod = (ll)1e9 + 7;
const ll ns = 97;

mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

struct kek {
	int x, i;

	bool operator < (const kek& other) const {
		return x < other.x;
	}
};

signed main () {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	int n, m, k;
	cin >> n >> m >> k;
	vector<int> goo (n), moo (m);
	cinv (goo);
	cinv (moo);
	sort (all (goo));
	sort (all (moo));
	int delta = inf;
	for (int i = k - 1; i < n; i += k) {
		chkmin (delta, goo[i] - i / k);
	}
	chkmin (delta, goo.back () - (n - 1) / k);
	if (delta < 0) {
		cout << -1;
		exit (0);
	}
	vector<kek> a (n), b (m);
	fr (i, n) a[i] = {goo[i], -1};
	fr (i, m) b[i] = {moo[i], i};
	stack<kek> t;
	vector<kek> lol (n + m);
	merge (all (a), all (b), lol.begin ());
	int cnt = 0;
	fr (i, sz (lol)) {
		dbg (lol[i].x);
		dbg (lol[i].i);
		dbg (cnt);
		dbg (cnt / k);
		if (lol[i].x >= cnt / k) {
			if (lol[i].i != -1) t.push (lol[i]);
			++cnt;
		} else {
			if (lol[i].i == -1) {
				while (lol[i].x < cnt / k) {
					t.pop ();
					--cnt;
				}
				++cnt;
			}
		}
		// ++cnt;
	}
	cout << sz (t) << '\n';
	while (!t.empty ()) {
		cout << t.top ().i + 1 << ' ';
		t.pop ();
	}






}