#include <iostream>
#include <algorithm>
using namespace std;
pair<int,int> orders[100000];
int n,d,m;
bool works(int x)
{
int point = 0;
//cout << x << endl;
for(int i=1; i<=n; i++)
{
for(int j=0; j<x; j++)
{
if(orders[point].first>i)
break;
if(i>(orders[point].first+d))
return false;
//cout << point << " ";
point++;
if(point==m)
break;
}
//cout << endl;
if(point==m)
break;
}
if(point<m)
return false;
return true;
}
int main(){
cin >> n >> d >> m;
for(int i=0; i<m; i++)
{
cin >> orders[i].first;
orders[i].second = i+1;
}
sort(orders, orders+m);
int a = 1;
int b = m;
while(a!=b)
{
int mid = (a+b)/2;
if(works(mid))
b = mid;
else
a = mid+1;
//cout << endl;
}
cout << a << endl;
int point = 0;
for(int i=1; i<=n; i++)
{
for(int j=0; j<a; j++)
{
if(point==m)
break;
if(orders[point].first>i)
break;
cout << orders[point].second << " ";
point++;
}
cout << 0 << endl;
}
}
