#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector<ll> vi;
typedef vector<pair<ll,ll>> vpi;
typedef vector<vector<ll>> vvi;
const double EBS = 1e-9;
#define testCase ll t; cin >> t; while (t--)
#define fast ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define rep(f, s, i) for (ll i = f; i < s; i++)
#define getunique(v) {sort(v.begin(), v.end()); v.erase(unique(v.begin(), v.end()), v.end());}
#define calunique(v) disance(v.begin(),unique(v.begin(),v.end()));
#define popcount(i) __builtin_popcount(i)
#define el cout << "\n"
#define pb push_back
#define pf push_front
#define no cout << "NO\n"
#define yes cout << "YES\n"
#define all(v) v.begin(), v.end()
#define PII pair<ll,ll>
#define INF (ll)1e9
#define INFLL (ll)1e18
#define debug cout << "___________________________________" << endl
#define int ll
int n , d , k ;
vpi a ;
bool check(int num){
int idx = 0 ;
rep(1 , n + 1 , i){
int cnt = 0 ;
while(i >= a[idx].first && idx < k && cnt < num){
if (i > a[idx].first + d ) return 0 ;
idx++;
cnt++;
}
}
return 1 ;
}
int32_t main(){
fast ;
cin >> n >> d >> k ;
a = vpi(k);
rep(0 , k , i ) cin >> a[i].first , a[i].second = i+1 ;
sort(all(a));
int l = 0 , r = k ;
int ans = 0 ;
while(l < r ){
int mid = (l + r) / 2 ;
if (check(mid)){
ans = mid ;
r = mid ;
}else{
l = mid + 1;
}
}
cout << ans << endl ;
int idx = 0 ;
rep(0 , n , i){
int cnt = 0 ;
while(cnt < ans && idx < k ) cout << a[idx++].second << " " , cnt++ ;
cout << "0\n";
}
return 0;
}
