/*
* And in that light, I find deliverance.
* TASK : CEOI12 Jobs
* AUTHOR : Marszpace
*/
#include<bits/stdc++.h>
using namespace std;
int main(){
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
int n,d,m;
cin >> n >> d >> m;
vector<pair<int,int>> a(m,{0,0});
for(int i=0;i<m;i++){
a[i].second=i;
cin >> a[i].first;
}
sort(a.begin(),a.end());
int l=1,r=1000005;
while(r-l>1){
int mid=(l+r)/2;
queue<int> q;
for(auto [tt,id]:a){
q.push(tt);
}
bool can=true;
for(int i=1;i<=n;i++){
if(!q.empty() && q.front()+d<i){can=false;break;}
int dd=0;
while(!q.empty() && q.front()<=i && dd<mid){
q.pop();dd++;
}
}
if(can){
r=mid;
}
else{
l=mid;
}
}
cout << r << "\n";
queue<pair<int,int>> q;
for(auto p:a){
q.push(p);
}
bool can=true;
for(int i=1;i<=n;i++){
if(!q.empty() && q.front().first+d<i){can=false;break;}
int dd=0;
while(!q.empty() && q.front().first<=i && dd<r){
cout << q.front().second+1 << " ";
q.pop();dd++;
}
cout << "0\n";
}
return 0;
}
