#include <iostream>
#include <complex>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <numeric>
#include <cstring>
#include <ctime>
#include <cstdlib>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <cmath>
#include <bitset>
#include <cassert>
#include <queue>
#include <stack>
#include <deque>
#include <random>
using namespace std;
template<typename T1, typename T2> inline void chkmin(T1 &a, T2 b) {if (a > b) a = b;}
template<typename T1, typename T2> inline void chkmax(T1 &a, T2 b) {if (a < b) a = b;}
#define files(FILENAME) read(FILENAME); write(FILENAME)
#define read(FILENAME) freopen((FILENAME + ".in").c_str(), "r", stdin)
#define write(FILENAME) freopen((FILENAME + ".out").c_str(), "w", stdout)
#define all(c) (c).begin(), (c).end()
#define sz(c) (int)(c).size()
#define left left228
#define right right228
#define y1 y1228
#define mp make_pair
#define pb push_back
#define y2 y2228
#define rank rank228
using ll = long long;
using ld = long double;
const string FILENAME = "input";
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
//read(FILENAME);
int days, delay, n;
cin >> days >> delay >> n;
vector<int> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i];
}
vector<int> ord(n);
iota(all(ord), 0);
sort(all(ord), [&](int x, int y) {
return a[x] < a[y];
});
auto check = [&](int x) {
int pos = 0;
for (int i = 1; i <= days; i++) {
int today = 0;
while (today < x && pos < n) {
int cand = a[ord[pos]];
if (i < cand) {
break;
}
if (i > cand + delay) {
return false;
}
pos++;
today++;
}
}
return pos == n;
};
int l = 1, r = n, sol = -1;
while (l <= r) {
int m = (l + r) >> 1;
if (check(m)) {
r = m - 1;
sol = m;
} else {
l = m + 1;
}
}
cout << sol << '\n';
int pos = 0;
for (int i = 1; i <= days; i++) {
int today = 0;
while (today < sol && pos < n) {
int cand = a[ord[pos]];
if (i < cand) {
break;
}
cout << ord[pos] + 1 << ' ';
pos++;
}
cout << 0 << '\n';
}
return 0;
}
