//wait darn
#include<bits/stdc++.h>
using namespace std;
#define MAXM 1000005
#define x first
#define y second
int M, N, D;
pair<int,int> job[MAXM];
void read()
{
ios_base::sync_with_stdio(false);
cin.tie();
cin >> N >> D >> M;
for(int i = 0; i < M; i++)
{
cin >> job[i].x;
job[i].x += D;
job[i].y = i+1;
}
sort(job,job+M);
}
bool test(long long mech)
{
if(mech < (M+N)/N)
{
if(mech*N < M)
return false;
}
for(int i = 0; i < M;i++)
{
if(job[i].x < ((i/mech)+1))
return false;
}
return true;
}
void print(long long mech)
{
ios_base::sync_with_stdio(false);
cin.tie();
cout << mech << endl;
int d = 0;
for(int i = 0; i < M;i++)
{
cout << job[i].y << " ";
if((i+1)%mech == 0)
{
cout << 0 << endl;
d++;
}
}
for(; d < N; d++)
cout << 0 << endl;
}
int solve()
{
int lo = 1, hi = M, mi;
while(hi - lo > 1)
{
mi = (lo+hi)/2;
if(test(mi))
hi = mi;
else
lo = mi;
}
if(test(lo))
return lo;
return hi;
}
int main()
{
read();
print(solve());
}
