#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
#define endl "\n"
long long a,b,c,d,e,f,m,n,h,l,r,k,x,y,ans,sum;
// bool sortcol(const vector<int>& v1, const vector<int>& v2){
// return v1[1] < v2[1];
// }
int C, D, K, N, M;
vector<vector<int>>A(1000005, vector<int>(2));
bool bin_search(int mid){
int limit = A[0][0] + D;
int count = 0;
int day_count = 1;
for(int i = 0; i < M;i++){
if(day_count > A[i][0]){
return false;
}
if(A[i][0] <= limit and count < mid){
count++;
}
else{
++day_count;
limit = A[i][0] + D;
count = 0;
if(A[i][0] <= limit and count < mid){
count++;
}
}
// cout<<A[i][0]<<" "<<day_count<<" "<<count<<" "<<mid<<endl;
}
// cout<<day_count<<" "<<mid<<endl;
return day_count <= N;
}
int32_t main(){
// freopen("angry.in", "r", stdin);
// freopen("angry.out", "w", stdout);
cin>>N>>D>>M;
for(int i = 0; i < M; i++){
cin>>a;
A[i][0] = a;
A[i][1] = i + 1;
}
sort(A.begin(), A.begin() + M);
// for(int i = 0; i < M; i++){
// cout<<A[i][0]<<" "<<A[i][1]<<endl;
// }
int left = 0, right = M;
while(left < right){
int mid = left + ((right - left) / 2);
if(bin_search(mid)){
right = mid;
}
else left = mid + 1;
}
cout<<right<<endl;
int k = 0;
for(int i = 0; i < N; i++){
int j = right;
while(k < M and j--){
cout<<A[k][1]<<" ";
k++;
}
cout<<0<<endl;
}
return 0;
}
