import java.io.*;
import java.util.*;
public class jobs{
static int N; static int M;
static List<Job> jobs;
static PrintWriter pr;
public static void main(String []args) throws IOException{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
pr = new PrintWriter(new OutputStreamWriter(System.out));
StringTokenizer st = new StringTokenizer(br.readLine());
N = Integer.parseInt(st.nextToken()); int D = Integer.parseInt(st.nextToken()); M = Integer.parseInt(st.nextToken());
jobs = new ArrayList<>();
st = new StringTokenizer(br.readLine());
for(int i=1; i<=M; i++){
int id = Integer.parseInt(st.nextToken());
jobs.add(new Job(i, id, id+D));
}
jobs.sort((j1, j2)->Integer.compare(j1.end, j2.end));
int minmachine=binsearchLeft(0, M);
printRes(minmachine);
pr.close();
}
static boolean isGood(int machines){
Queue<Job> q= new LinkedList<Job>();
for(Job j: jobs){
q.offer(j);
}
for(int i=1; i<=N; i++){
int nleft = machines;
while(nleft>0 && q.peek()!=null){
Job top = q.peek();
if(top.start >i){
break;
}
else{
q.poll();
nleft--;
}
}
}
if(q.isEmpty()){
return true;
}
else{return false;}
}
static void printRes(int min){
pr.println(min);
Queue<Job> q= new LinkedList<Job>();
for(Job j: jobs){
q.offer(j);
}
for(int i=1; i<=N; i++){
int nleft = min;
while(nleft>0 && q.peek()!=null){
Job top = q.peek();
if(top.start >i){
break;
}
else{
pr.print(top.id+" ");
q.poll();
nleft--;
}
}
pr.print(0);
pr.println();
}
}
static int binsearchLeft(int left, int right){
if(left>right){
return -1;
}
int mid = left + (right-left)/2;
if(isGood(mid)){
int res = binsearchLeft(left, mid-1);
if(res==-1){return mid;}
else{return res;}
}
else{
return binsearchLeft(mid+1, right);
}
}
static class Job{
int id; int start; int end;
public Job(int id, int start, int end){
this.id = id; this.start = start; this.end=end;
}
}
}
