#include <iostream>
/*
#include <fstream>
std::ifstream cin ("shuffle.in");
std::ofstream cout ("shuffle.out");
*/
using namespace std;
#include <vector>
#include <set>
#include <unordered_set>
#include <map>
#include <algorithm>
#include <queue>
#include <string>
#include <cstring>
#include <cstdio>
#include <iomanip>
#include <list>
#include <numeric>
#include <cmath>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define vi vector<int>
#define vl vector<ll>
#define vvi vector<vi>
#define vvl vector<vl>
#define vpi vector<pair<int,int>>
#define vb vector<bool>
#define pb push_back
#define mp make_pair
#define pi pair<int, int>
#define FR(x, a, b) for(int x = a; x < b; x++)
#define F(x, b) FR(x, 0, b)
#define f first
#define s second
#define ll long long
using namespace std;
/*
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
*/
int main(){
int n, k, m; cin >> n >> k >> m;
vi a(n); vpi p(m);
F(i, m){cin >> p[i].f; p[i].f--; a[p[i].f]++; p[i].s = i + 1;}
sort(all(p));
auto check = [&](int x){
int d = 0, dead = 0;
while(d < n){
int dl = x;
while(dl > 0 && d < n){
while(a[d] == 0 && d < n){d++;}
int amt = min(a[d], dl);
a[d] -= amt;
dl -= amt;
}
while(a[d] == 0 && d < n){d++;}
dead++;
if(dead - d > k){ return false;}
}
return true;
};
int l = 1, r = 1e6;
while(l < r){
int mi = (r + l)/2;
auto t = a;
if(check(mi)){
r = mi;
} else {
l = mi + 1;
}
a = t;
}
cout << l << endl;
int po = 0;
F(i, n){
int c = l;
while(c > 0 && po < m){
cout << p[po].s << " ";
c--;
po++;
}
cout << 0 << endl;
}
return 0;
}
