import java.io.*;
import java.util.*;
public class jobs {
static ArrayList<ArrayList<Integer>> schedule = new ArrayList<>();
static int N, D, M;
public static void main(String... args) throws IOException {
// BufferedReader reader = new BufferedReader(new FileReader("input.in"));
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
PrintWriter writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
StringTokenizer st = new StringTokenizer(reader.readLine());
N = Integer.parseInt(st.nextToken());
D = Integer.parseInt(st.nextToken());
M = Integer.parseInt(st.nextToken());
st = new StringTokenizer(reader.readLine());
Request[] jobs = new Request[M];
for (int i = 0; i < M; i++) {
jobs[i] = new Request(i + 1, Integer.parseInt(st.nextToken()));
}
Arrays.sort(jobs, Comparator.comparingInt(j -> j.day));
// System.out.println(Arrays.toString(jobs));
int lo = 1;
int hi = M;
while (lo < hi) {
int mid = lo + (hi - lo) / 2;
try {
Return r = test(mid, jobs);
if (r.worked) {
hi = mid;
schedule = r.schedule;
} else {
lo = mid + 1;
}
} catch (RuntimeException e) {
System.out.println(Arrays.toString(e.getStackTrace()));
}
}
System.out.println(lo);
for (ArrayList<Integer> ds : schedule) {
for (int z : ds) {
System.out.print(z + " ");
}
System.out.println(0);
}
}
static Return test(int numMachines, Request[] jobs) {
ArrayList<ArrayList<Integer>> schedule = new ArrayList<>();
for (int i = 0; i < N; i++) schedule.add(new ArrayList<>());
int reqNum = 0;
for (int day = 1; day <= N; day++) {
for (int j = 0; j < numMachines; j++) {
if (jobs[reqNum].day > day) break;
if (jobs[reqNum].day + D >= day) {
schedule.get(day - 1).add(jobs[reqNum].id);
reqNum++;
} else {
return new Return(false, schedule);
}
if (reqNum == M) return new Return(true, schedule);
}
}
return new Return(false, schedule);
}
static class Return {
boolean worked;
ArrayList<ArrayList<Integer>> schedule;
public Return(boolean worked, ArrayList<ArrayList<Integer>> schedule) {
this.worked = worked;
this.schedule = schedule;
}
}
static class Request {
int id;
int day;
public Request(int id, int day) {
this.id = id;
this.day = day;
}
@Override
public String toString() {
return "Request{" +
"id=" + id +
", day=" + day +
'}';
}
}
}
