import java.util.*;
public class jobs {
static int n, d, m;
static ArrayList<Job> jobs = new ArrayList<>();
public static void main(String[] args){
Scanner in = new Scanner(System.in);
n = in.nextInt(); d = in.nextInt(); m = in.nextInt();
for(int i = 0; i < m; i++){
jobs.add(new Job(in.nextInt(), i));
}
Collections.sort(jobs);
int s = 1, e = 1000000000;
while (s != e) {
int mid = (s+e)/2;
if (is_pos(mid)) {
e = mid;
} else {
s = mid + 1;
}
}
int ans = s;
System.out.println(ans);
int i = 0, j = 0;
for (int day = 1; day <= n; day++) {
while (j < jobs.size() && j - i + 1 <= ans && jobs.get(j).job <= day) {
j++;
}
while (i < j) {
System.out.print(jobs.get(i).day + 1 + " ");
i++;
}
System.out.println("0");
}
}
static boolean is_pos(int mid) {
int i = 0, j = 0;
for (int day = 1; day <= n; day++) {
while (j < jobs.size() && j - i + 1 <= mid && jobs.get(j).job <= day) {
j++;
}
while (i < j) {
if (day - jobs.get(i).job > d) return false;
i++;
}
}
return i >= n;
}
static class Job implements Comparable<Job>{
int job, day;
public Job(int job, int day) {
this.job = job;
this.day = day;
}
public int compareTo(Job o) {
return this.job-o.job;
}
}
}
