// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
using namespace std;
#define int long long
#define endl "\n"
#define fi first
#define se second
const int M=1203465797;
const int inf = 1e14;
const int LOG=18;
const int N=2e3+5;
int n , m , c , w , k , t=1 , q=1 , x , y , z , l , r;
void solve(){
cin >> n >> k >> m;
vector<pair<int,int>>a(m);
for (int i=0;i<m;i++){
cin >> a[i].fi;
a[i].se=i;
}
sort(a.begin(),a.end());
vector<int>d(n+1);
for (auto i:a){
d[i.fi]++;
}
int l=0;
int h=m;
int mi=(l+h)/2;
while (l<h){
c=0;
bool f=1;
queue<int>o;
for (int i=1;i<=n;i++){
for (int j=0;j<d[i];j++){
o.push(i);
}
x=mi;
while (x-- and o.size()){
o.pop();
}
if (o.size() and o.front()<=i-k){
f=0;
break;
}
}
if (f and o.empty()){
h=mi;
}
else{
l=mi+1;
}
mi=(l+h)/2;
}
cout << mi << endl;
queue<int>o;
vector<vector<int>>li(n+1);
for (int i=0;i<m;i++){
li[a[i].fi].push_back(a[i].se+1);
}
for (int i=1;i<=n;i++){
for (int j:li[i]){
o.push(j);
}
x=mi;
while (x-- and o.size()){
cout << o.front() << " ";
o.pop();
}
cout << 0 << endl;
}
}
signed main()
{
// #ifndef ONLINE_JUDGE
// freopen("input.txt","r" ,stdin);
// freopen("output.txt","w",stdout);
// #endif
ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
cin.tie(0), cout.tie(0);//DO NOT USE IN INTERACTIVE
cout << fixed << setprecision(9);
srand(time(0));
// int t=1;
// cin >> t;
for (int _=1;_<=t;_++){
solve();
q++;
}
}
