#include <bits/stdc++.h>
using namespace std;
int main()
{
int n, d, m;
cin >> n >> d >> m;
vector <pair<int, int>> jobs(m);
for (int i = 0; i < m; i++){
cin >> jobs[i].first;
jobs[i].second = i;
}
sort(begin(jobs), end(jobs));
int l = 1, r = m;
while (l <= r){
int machines = (l+r) / 2;
int i = 0;
for (int day = 1; day <= n; day++){
for (int j = 0; j < machines; j++){
if (i >= m)
break;
if (day - jobs[i].first <= d && day >= jobs[i].first)
i++;
else
break;
}
if (i >= m)
break;
}
if (i >= m)
r = machines - 1;
else
l = machines + 1;
}
cout << l << '\n';
int i = 0;
for (int day = 1; day <= n; day++){
for (int j = 0; j < l; j++){
if (i >= m)
break;
if (day - jobs[i].first <= d && day >= jobs[i].first){
cout << jobs[i].second + 1 << ' ';
i++;
}
}
cout << 0 << '\n';
}
}
