#include <iostream>
#include <algorithm>
using namespace std;
int N, D, M; //days, delay, jobs
struct job
{
int i; //ind
int d; //day
};
bool operator < (job A, job B)
{
return A.d < B.d;
}
job J[1000000];
int b_search(int a, int b)
{
// cout << a << ' ' << b << '\n';
if(a == b) return a;
int m = (a+b)/2;
int done = 0; //number of jobs done
for(int i = 1; i <= N; i++)
{
if(done < M && J[done].d + D < i)
{
// cout << i << "too long" << '\n';
return b_search(m+1, b);
}
for(int j = 0; j < m && done < M && J[done].d <= i; j++)
{
done++;
}
}
if(done < M) return b_search(m+1, b);
else return b_search(a, m);
}
int main()
{
cin >> N >> D >> M;
for(int i = 0; i < M; i++)
{
cin >> J[i].d;
J[i].i = i+1;
}
sort(J, J+M);
int m = b_search(1, M);
int done = 0;
cout << m << '\n';
for(int i = 1; i <= N; i++)
{
for(int j = 0; j < m && done < M && J[done].d <= i; j++)
{
cout << J[done].i << ' ';
done++;
}
cout << "0\n";
}
}
