#pragma GCC optimize("O3")
#pragma GCC target("avx,avx2,sse,sse2,sse3,sse4,popcnt,fma")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define fastio() ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
typedef long long ll;
typedef unsigned long long ull;
typedef long double lld;
#define fo(iter, start_value, less_than) for(int iter = start_value; iter<less_than; iter++)
#define noans cout<<"-1"
#define zero cout<<"0"
#define nline "\n"
#define space " "
#define MSBll(n) __lg(n)
#define vi vector<int>
#define vpii vector<pair<int, int> >
#define vvi vector<vector<int> >
#define set_bits __builtin_popcountll
#define getunique(x) {sort(all(x)); x.erase(unique(all(x)), x.end());}
#define mem(x, val) memset(x, val, sizeof(x))
// const double PI = 3.141592653589793238462;
// const int MOD = 1e9+7;
// const int MOD = 998244353;
// const ll INF = 1e18;
const int N = 1e6+6;
// const int N = 2e5+5;
// const int N = 3e5+5;
// const int MX = INT_MAX;
// const int MN = INT_MIN;
#define yes cout<<"YES"
#define no cout<<"NO"
struct point{
int x;
int id;
};
int n, ex, days;
vector<point> arr(N+1);
bool chk(int x){
int d = 1, i = x;
while(i<=n){
if(d <= arr[i].x + ex){
i += x;
d++;
}else{
return false;
}
}
return true;
}
void fun(){
cin>>days>>ex>>n;
arr.resize(n+1);
for(int i = 1; i<=n; i++){
cin>>arr[i].x;
arr[i].id = i;
}
sort(arr.begin() + 1, arr.end(), [](point p1, point p2){
return p1.x < p2.x;
});
int l = 1, r = n;
while(l<=r){
int mid = l + (r-l)/2;
if(chk(mid)){
r = mid - 1;
}else{
l = mid + 1;
}
}
int rq = r+1;
vector<vector<int> > ans;
for(int i = 1; i<=n;){
int cnt = 0;
vector<int> tmp;
while(i<=n and cnt<rq){
tmp.push_back(arr[i].id);
cnt++;
i++;
}
ans.push_back(tmp);
}
cout<<rq<<nline;
for(auto v: ans){
for(int x: v) cout<<x<<space;
cout<<"0 "<<nline;
}
for(int i = ans.size(); i<days; i++) zero<<nline;
}
signed main() {
// #ifndef ONLINE_JUDGE
// freopen("Error.txt", "w", stderr);
// #endif
fastio();
int _CASE = 1;
// int _TC = 1;cin>>_TC;while(_TC--)
// cout<<"Case #"<<_CASE++<<": ",
fun(),cout<<"\n";
return 0;
}
