#include <bits/stdc++.h>
using namespace std;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
int n, d, m;
cin >> n >> d >> m;
vector<pair<int, int>> a(m);
for (int i = 0; i < m; ++i){
cin >> a[i].first;
a[i].second = i;
}
sort(a.begin(), a.end());
auto Work = [&](int num){
int j = 0;
for (int day = 1; day <= n; ++day){
int k = 0;
while (j < m && k < num){
if (day > a[j].first + d){
return false;
}
++j;
++k;
}
}
return (j == m);
};
while(true){}
int lo = 1, hi = m, ans = -1;
while (lo <= hi){
int mid = lo + (hi - lo) / 2;
if (Work(mid)){
ans = mid;
hi = mid - 1;
}else{
lo = mid + 1;
}
}
cout << ans << "\n";
int j = 0;
for (int i = 0; i < n; ++i){
int k = 0;
while (k < ans && j < m){
cout << a[j].second + 1 << " ";
++j;
++k;
}
cout << "0\n";
}
/*
8 2 12
1 2 4 2 1 3 5 6 2 3 6 4
*/
}
