#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define pii pair<int,int>
#define fi first
#define se second
#define endl '\n'
int n , m , d;
const int MAXN = 1e5 +7 ;
vector<int> adj[MAXN];
bool bs(int mid , bool h )
{
queue<pii> q;
for(int i = 1 ;i <=n;i++){
for(auto j : adj[i])
q.push({i,j});
for(int j = 0 ;j <mid && q.size() ;j++)
{
if(i-q.front().fi >d)return 0;
if(h)cout<<q.front().se<<' ';
q.pop();
}
if(h) cout<<'0'<<endl;
}
return 1 ;
}
int main ()
{
cin >> n >> d >> m;
for(int i = 1 ;i <= m ;i++)
{
int h ;
cin>>h;
adj[h].pb(i);
}
int l = 1 , r = m ;
while(l!=r)
{
int mid = (l+r)/2;
if(bs(mid,0))r=mid;
else l =mid+1;
}
cout<<l<<endl;
bs(l,1);
return 0 ;
}
