import java.util.*;
import java.io.*;
public class jobs {
static class Job implements Comparable<Job> {
public int id, day;
public Job(int i, int d) {
id = i;
day = d;
}
public int compareTo(Job o) {
return this.day - o.day;
}
}
public static void main(String[] args) throws Exception {
Kattio in = new Kattio();
int days = in.nextInt();
int d = in.nextInt();
int m = in.nextInt();
Job[] jobs = new Job[m];
for (int i = 0; i < m; i++) {
int assign = in.nextInt();
jobs[i] = new Job(i + 1, assign);
}
Arrays.sort(jobs);
int l = 0;
int r = m;
while (l < r) {
int mid = (l + r)/2;
if (checkValid(mid, days, d, m, jobs)) {
r = mid;
} else {
l = mid + 1;
}
}
System.out.println(l);
printer(l, days, d, m, jobs);
}
public static boolean checkValid(int macs, int days, int d, int m, Job[] jobs) {
int i = 0;
int count = 1;
while (count <= days && i < m) {
int work = 0;
while (work < macs && i < m) {
if (jobs[i].day > count) {
break;
}
if (count > jobs[i].day + d) {
return false;
}
work++;
i++;
}
count++;
}
if (i < m) {
return false;
}
return true;
}
public static void printer(int macs, int days, int d, int m, Job[] jobs) {
StringBuilder sb = new StringBuilder();
int i = 0;
int count = 1;
while (count <= days && i < m) {
int work = 0;
while (work < macs && i < m) {
if (jobs[i].day > count) {
break;
}
sb.append(jobs[i].id);
sb.append(" ");
work++;
i++;
}
count++;
sb.append("0\n");
}
while (count <= days) {
sb.append("0\n");
count++;
}
System.out.println(sb);
}
static class Kattio extends PrintWriter {//Kattio
private BufferedReader r;
private StringTokenizer st;
// standard input
public Kattio() { this(System.in, System.out); }
public Kattio(InputStream i, OutputStream o) {
super(o);
r = new BufferedReader(new InputStreamReader(i));
}
// USACO-style file input
public Kattio(String problemName) throws IOException {
super(problemName + ".out");
r = new BufferedReader(new FileReader(problemName + ".in"));
}
// returns null if no more input
public String next() {
try {
while (st == null || !st.hasMoreTokens())
st = new StringTokenizer(r.readLine());
return st.nextToken();
} catch (Exception e) { }
return null;
}
public int nextInt() { return Integer.parseInt(next()); }
public double nextDouble() { return Double.parseDouble(next()); }
public long nextLong() { return Long.parseLong(next()); }
}
}
