#include <bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
int n,m,k,mc;
map<int,vector<int>> mp;
vector<int> v;
void psh(int n){
for(auto x : mp[n])v.push_back(x);
}
int main(){
cin.tie(nullptr)->sync_with_stdio(false);
cin >> n >> m >> k;
for(int i=1;i<=k;i++){
int x;cin >> x;
mp[x].push_back(i);
}
int sum = 0,mx;
for(int i=1;i<=1+m;i++){
sum += mp[i].size();
psh(i);
}
mx = sum;
for(int i=m+2;i<=k;i++){
sum+=mp[i].size();
sum-=mp[i-m-1].size();
psh(i);
mx = max(mx,sum);
}
mc = mx/(m+1);
cout << mc << "\n";
int tmp = 0;
for(int i=1;i<=n;i++){
for(int j = tmp;j<tmp+mc && v[j] != 0;j++){
cout << v[j] << " ";
}tmp+=mc;
cout << "0 \n";
}
return 0;
}
/*
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
*/
