import java.io.*;
import java.util.*;
public class jobs {
static class Point implements Comparable<Point> {
int time;
int position;
public Point(int time, int position){
this.time = time;
this.position = position;
}
@Override
public int compareTo(Point c) {
return Integer.compare(time, c.time);
}
@Override
public String toString() {
return time+" "+position;
}
}
public static int n, d, m;
public static ArrayList<ArrayList<Integer>> jobs = new ArrayList<>();
public static String s = "";
public static void main(String[] args) {
Scanner fin = new Scanner(System.in);
n = fin.nextInt();
d = fin.nextInt();
m = fin.nextInt();
for (int i=0; i<n-d; i++) {
jobs.add(new ArrayList<>());
}
for (int i=0; i<m; i++) {
jobs.get(fin.nextInt()-1).add(i);
}
int low = 1;
int high = m;
while (low < high) {
int mid = (low+high)/2;
if (works(mid)) {
high = mid;
}
else {
low = mid+1;
}
}
System.out.println(low);
System.out.println(s);
fin.close();
}
public static boolean works(int numMachines) {
PriorityQueue<Point> pq = new PriorityQueue<>();
String tempS = "";
for (int i=0; i<n; i++) {
if (i < n-d) {
for (int j=0; j<jobs.get(i).size(); j++) {
pq.add(new Point(i, jobs.get(i).get(j)));
}
}
if (!tempS.equals("")) {
tempS += "\n";
}
for (int j=0; j<numMachines; j++) {
if (pq.isEmpty()) {
break;
}
Point p = pq.poll();
if (p.time+d < i) {
return false;
}
tempS += (p.position+1)+" ";
}
tempS += "0";
}
if (!pq.isEmpty()) {
return false;
}
s = tempS;
return true;
}
}
