#include <bits/stdc++.h>
using namespace std;
signed main(){
ios::sync_with_stdio(false);
cin.tie(0);
int n, d, m; cin >> n >> d >> m;
vector<pair<int, int>> x(m);
for(int i = 0; i < m; i++){
cin >> x[i].first;
x[i].second = i;
}
sort(x.begin(), x.end());
int low = 1;
int top = m;
int ns = 0;
while(low <= top){
int mid = (low+top)/2;
int it = 0;
for(int i = 1; i <= n; i++){
for(int y = 0; y < mid && it >= 0 && it < m; y++){
if(x[it].first > i) break;
if(i-x[it].first <= d){
it++;
}else{
it = -1;
break;
}
}
}
if(it == m){
top = mid-1;
ns = mid;
}else{
low = mid+1;
}
}
cout << ns << "\n";
int mid = ns;
int it = 0;
for(int i = 1; i <= n; i++){
for(int y = 0; y < mid && it < m; y++){
if(x[it].first > i) break;
cout << x[it].second+1 << " ";
it++;
}
cout << 0 << "\n";
}
return 0;
}
