/*
TASK: Job Scheduling (CEOI2012)
LANG: C++
AUTHOR: Yowaine
*/
#include <bits/stdc++.h>
using namespace std;
#define PII pair<int,int> // {day , idx}
#define day first
#define idx second
#define newline cout << "\n"
#define all(x) x.begin() , x.end()
queue <PII> q;
vector <PII> vec;
int n , d , m;
bool is_possible(int mid){
int j = 0;
int sz = vec.size();
for (int i = 1 ; i <= n ; i++){
if (j >= sz) return true;
if (vec[j].day > i) continue;
if (i > vec[j].day + d) return false;
j += mid;
}
return true;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
cout.tie(0);
cin >> n >> d >> m;
for (int i = 1 ; i <= m ; i++){
int num; cin >> num;
vec.push_back({num , i});
}
sort(all(vec));
int lo = 1 , hi = 1e6;
int ans = 0;
while(lo <= hi){
int mid = lo + (hi - lo)/2;
if (is_possible(mid)){
ans = mid;
hi = mid - 1;
}
else{
lo = mid + 1;
}
}
for (auto x : vec) q.push(x);
cout << ans;
newline;
for (int i = 1; i <= n ; i++){
for (int cnt = 1 ; cnt <= ans ; cnt++){
if (q.front().day > i) break;
if (q.empty()){
break;
}
cout << q.front().idx << " ";
q.pop();
}
cout << "0";
newline;
}
return 0;
}
/*
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
8 0 10
6 6 6 6 6 6 6 6 6 6
*/
