#include <bits/stdc++.h>
using namespace std;
#define MAXN 2000000
#define int long long
struct request{
int day;
int id;
};
bool sortbyday(request &r1, request &r2){
return r1.day<r2.day;
}
int numreqs, numdays, maxdelay;
request jobreqs[MAXN];
bool works(int nummach){
int day = 1;
//check jobreqs by chucks of size nummach and see if any of the jobs are overdue
while(numreqs>(day-1)*nummach){
for(int i = 0; i < nummach; i++){
if(jobreqs[(day-1)*nummach+i].day<day-maxdelay){ //overdue job check
return false;
}
}
day++;
}
return true;
}
signed main(){
cin>>numdays>>maxdelay>>numreqs;
int day;
for(int i = 1; i <= numreqs; i++){
cin>>day;
jobreqs[i-1] = {day, i};
}
sort(jobreqs, jobreqs+numreqs, sortbyday);
int lo = 1, hi = MAXN;
while(lo!=hi){
int mid = (lo+hi)/2;
if(works(mid)){
hi = mid;
}
else{
lo = mid + 1;
}
}
cout<<lo<<endl;
int index = 0;
for(int i = 0; i < numdays; i++){
for(int j = 0; j < lo; j++){
if(index < numreqs){
cout<<jobreqs[index].id<<" ";
index++;
}
}
cout<<0<<endl;
}
}
