#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e6+5;
vector<pair<int,int>> jobs(MAXN);
int N,M,D;
bool check(int x){
for(int i = 1;i<=M;++i){
if(i/x > jobs[i].first+D) return false;
}
if(M/x > N) return false;
return true;
}
int main()
{
cin >> N >> D >> M;
jobs.resize(M+1);
for(int i = 1;i<=M;++i){cin >> jobs[i].first; jobs[i].second = i;}
sort(jobs.begin(),jobs.end());
//for(auto p : jobs) cout << p.first << " ";
//cout << "\n";
int lo = 1, hi = MAXN;
while(lo < hi){
int mid = (lo+hi)/2;
if(check(mid)){
hi = mid;
}
else{
lo = mid+1;
}
}
cout << lo << "\n";
int cur = 1;
for(int i = 1;i<=M;++i){
if(i/lo == cur+1){
cout << "0 \n" << jobs[i].second << " ";
cur++;
}
else cout << jobs[i].second << " ";
}
cout << "\n";
while(cur < N){
cout << "0\n";
cur++;
}
return 0;
}
