#include<vector>
#include <iostream>
#include<algorithm>
#include<queue>
#include<map>
#include<bitset>
#include<set>
#include<cstdlib>
#define f first
#define sec second
#define pb push_back
typedef long long ll;
using namespace std;
int n,d,m;
vector<pair<int,int>> arr;
int zlicz[100005];
int zlicz2[100005];
bool spr(int x)
{ for(int i=1;i<=n-d;i++)zlicz2[i]=zlicz[i];
int curr=1;
for(int i=1;i<=n;i++)
{
if(i-curr>d)return 0;
int ile=0;
while(ile<x&&curr<=i)
{
int od=min(zlicz2[curr],x-ile); ile+=od;
zlicz2[curr]-=od; if(!zlicz2[curr])curr++;
}
if(curr>n-d)return 1;
}
return 0;
}
int bin(int lo,int hi)
{
while(lo<hi)
{
int mid=lo+(hi-lo)/2;
if(spr(mid))hi=mid; else lo=mid+1;
}
return lo;
}
int main()
{ ios_base::sync_with_stdio();
cin>>n>>d>>m;
for(int i=0;i<m;i++)
{int a; cin>>a; arr.pb({a,i+1}); zlicz[a]++;} sort(arr.begin(),arr.end());
int res=bin(1,m+1);
cout<<res<<endl;
int curr=0;
for(int i=1;i<=n-d;i++)
{int licz=0;
if(curr==m){cout<<'0'<<endl; continue;}
while(licz<res)
{licz++;
if(arr[curr].f<=i){cout<<arr[curr].sec<<' '; curr++;}
}
cout<<'0'<<endl;
}
for(int i=0;i<d;i++)cout<<'0'<<endl;
return 0;
}
