import java.util.*;
import java.io.*;
public class jobs {
static Kattio io = new Kattio();
static int numDays;
static int delay;
static int numReqs;
static Request[] requests;
static int[] reqCount;
public static void main(String[] args) {
numDays = io.nextInt();
delay = io.nextInt();
numReqs = io.nextInt();
requests = new Request[numReqs];
reqCount = new int[numDays + 1];
for(int i = 0; i < numReqs; i++) {
int day = io.nextInt();
requests[i] = new Request(day, i + 1); // 1-indexed
}
Arrays.sort(requests);
// count how many requests per day
int reqPointer = 0;
for(int i = 1; i <= numDays; i++) {
while(reqPointer < numReqs && requests[reqPointer].day == i) {
reqCount[i]++;
reqPointer++;
}
}
// binary search for smallest value that works
int lo = 0;
int hi = numReqs;
while(lo < hi) {
int mid = (hi + lo) / 2;
if(machinesWork(mid)) {
hi = mid;
} else {
lo = mid + 1;
}
}
io.println(lo);
// print the schedule for each day
int requestsPointer = 0;
for(int day = 1; day <= numDays; day++) {
if(requestsPointer == numReqs) {
io.println(0); // no more requests
continue;
}
for(int i = 0; i < lo; i++) {
if(requests[requestsPointer].day > day) {
break;
}
io.print(requests[requestsPointer++].id + " ");
}
io.println("0");
}
io.close();
}
static boolean machinesWork(int amt) {
int fromPrev = 0;
for(int i = 1; i <= numDays; i++) {
if(amt * (delay + 1) < (reqCount[i] + fromPrev)) {
return false;
}
fromPrev = Math.max(0, reqCount[i] + fromPrev - amt);
}
return true;
}
static class Request implements Comparable<Request> {
int day;
int id;
public Request(int day, int id) {
this.day = day;
this.id = id;
}
public int compareTo(Request r) {
return Integer.compare(day, r.day);
}
}
static class Kattio extends PrintWriter {
private BufferedReader r;
private StringTokenizer st = new StringTokenizer("");
private String token;
// 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(new FileWriter(problemName+".out"));
r = new BufferedReader(new FileReader(problemName+".in"));
}
private String peek() {
if (token == null)
try {
while (!st.hasMoreTokens()) {
String line = r.readLine();
if (line == null) return null;
st = new StringTokenizer(line);
}
token = st.nextToken();
} catch (IOException e) { }
return token;
}
public boolean hasMoreTokens() { return peek() != null; }
public String next() {
String ans = peek();
token = null;
return ans;
}
public int nextInt() { return Integer.parseInt(next()); }
public double nextDouble() { return Double.parseDouble(next()); }
public long nextLong() { return Long.parseLong(next()); }
}
}
