#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define ll long long
#define pii pair<int, int>
#define soclose 1e-9
int N, K, M;
vector<pii> a;
vector<int> s;
bool f(int m) {
int l = 0, r = m - 1;
// m = 3 => 3 machine
//
int day = 1;
while (r < M) {
while (l <= r) {
if (a[l].first < day) return false;
l++;
}
day++;
r += m;
}
return true;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
//freopen("angry.in", "r", stdin);
//freopen("angry.out", "w", stdout);
cin >> N >> K >> M;
a.resize(M);
for (int i = 0; i < M; ++i) {
cin >> a[i].first;
a[i].first += K;
a[i].second = i + 1;
}
sort(all(a));
int l = 0, r = M;
while (r - l > 1) {
int m = (l + r) / 2;
if (f(m)) r = m;
else l = m;
}
cout << r << '\n';
int L = 0, R = r - 1;
int num = 0;
while (R < M) {
int b = 0;
while (L <= R) {
cout << a[L].second << " ";
b++;
L++;
}
while (b < r) cout << "0 ";
cout << "0\n";
num++;
R += r;
}
while (num < N) {
cout << "0\n";
num++;
}
return 0;
}
