#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <set>
#include <sstream>
#include <map>
#include <cstdio>
#include <queue>
#include <cmath>
#include <stack>
#include <cctype> // doda isupper
#define int long long // vse ti je long long
#define vi vector<int>
#define vpii vector<pair<int,int>>
#define oopt cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(false);
#define forn(i,n) for(int i = 0; i<n; i++)
#define forn1(i,n) for(int i = 1; i<=n; i++)
#define all(x) (x).begin(), (x).end()
#define pi pair<int,int>
#define vvi vector<vi>
#define vvc vector<vector<char>>
#define sz(x) (x).size()
#define pb push_back
#define str string
using namespace std;
int n,m,d;
vpii stranke;
vvi urnik(int meja){
vvi ans(n);
int req_num = 0;
for(int dan = 1; dan<=n; dan++){
forn(i,meja){
if(stranke[req_num].first > dan) break; // preveč naprej smo
if(dan - stranke[req_num].first > d) return {}; //ne gre
else{
ans[dan-1].push_back(stranke[req_num++].second+1);
}
if(req_num == m) return ans;
}
}
return {};
}
signed main() {
cin >> n >> d>> m;
stranke.resize(m); //kdaj + id
forn(i,m){
cin >> stranke[i].first; //stranke[i].first;
stranke[i].second = i;
}
sort(all(stranke));
int l = 1, r = m;
while(l<r){
int rob = (l+r)/2;
//cout << rob << "\n";
if(urnik(rob).empty()){
l = rob+1;
} else {
r = rob;
}
}
cout << l << "\n";
vvi ans = urnik(l);
forn(i,n){
for(int nekaj : ans[i]) cout << nekaj << " ";
cout <<"0\n";
}
return 0;
}
