#include <bits/stdc++.h>
using namespace std;
int const MAX=1e6+5;
int n,d,m;
struct request{
int day,pos;
bool operator<(request ot){
return day<ot.day;
}
}req[MAX];
int capacity;
void read(){
cin>>n>>d>>m;
int i;
for(i=1;i<=m;++i){
cin>>req[i].day;
req[i].pos=i;
}
sort(req+1,req+m+1);
}
bool check(int cap){
int i;
int id=1;
for(i=1;i<=n;++i){
int used=0;
while(id<=m && used<cap && req[id].day<=i){
++used;
++id;
}
}
return (id>m);
}
int bin_search(){
/// (]
int st=0,dr=m;
while(dr-st>1){
int mij=(st+dr)/2;
if(check(mij))
dr=mij;
else
st=mij;
}
capacity=dr;
return dr;
}
void plan_work(){
int i;
int id=1;
for(i=1;i<=n;++i){
int used=0;
while(id<=m && used<capacity && req[id].day<=i){
cout<<req[id].pos<<' ';
++used;
++id;
}
cout<<"0\n";
}
}
int main()
{
read();
cout<<bin_search()<<'\n';
plan_work();
return 0;
}
