#include <iostream>
#include <vector>
using namespace std;
int main() {
int n, d, m;
cin >> n >> d >> m;
vector<int> jobs[n];
for (int x = 0; x < m; x ++){
int a;
cin >> a;
jobs[a-1].push_back(x);
}
int lo = 0, hi = m;
while (lo <= hi){
int mid = lo + (hi-lo+1)/2;
int c = 0;
bool pos = true;
vector<int> nums;
for (int x = 0; x < n; x ++){
c += jobs[x].size();
c -= mid;
c = max(0, c);
if (c >= d*mid){
pos = false;
break;
}
}
if (pos){
hi = mid-1;
}else {
lo = mid+1;
}
}
int k = hi+1, c = 0;
cout << k << endl;
vector<int> stack;
for (int x = 0; x < n; x ++){
stack.insert(stack.begin(), jobs[x].begin(), jobs[x].end());
c += jobs[x].size();
for (int y = 0; y < min(c, k); y ++){
cout << stack.back()+1 << " ";
stack.pop_back();
}
c -= k;
c = max(0, c);
cout << "0\n";
}
return 0;
}
