#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef long double ld;
#define fi first
#define se second
#define mp make_pair
#define fastIO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define TEST freopen("in.txt","r",stdin);
#define ab(a) ((a < 0) ? (-(a)) : (a))
#define len(x) ((int)(x).size())
#define ones(x) __builtin_popcount((x))
#define all(x) x.begin(), x.end()
const int N = (int)1e5 + 999;
int n,d;
vector<int>R[N];
int has_done[N];
bool can(int k){
for(int i = 0;i < N; i ++ )
has_done[i] = 0;
int tt = 0;
for(int i = 1;i <= d;i ++ )
tt += len(R[i]);
if(tt >= (d + 1) * k)
return false;
int p = 1;
for(int i = d + 1;i <= n;i ++ ){
tt -= len(R[p]);
p++;
if(tt >= (d + 1) * k)
return false;
}
return true;
}
void output_solution(int answer){
cout << answer << "\n";
for(int j = 0;j < N;j ++ )
has_done[j] = 0;
int p = 1;
int tt;
for(int i = 1;i <= n;i ++ ){
tt = answer;
while(p <= i and tt > 0){
if(len(R[p]) == has_done[p]){
p++;
continue;
}
cout << R[p][has_done[p]] << " ";
has_done[p]++;
tt--;
}
cout << "0\n";
}
}
int main(){
fastIO;
int m;
cin >> n >> d >> m;
int x;
for(int i = 0;i < m;i ++ ){
cin >> x;
R[x].push_back(i + 1);
}
int lf = 0, rf = m + 1;
int md;
while(lf + 1 < rf){
md = (lf + rf) / 2;
if(can(md))
rf = md;
else
lf = md;
}
output_solution(rf);
return 0;
}
