import java.io.*;
import java.util.*;
public class jobs {
public static void main(String[] args) throws IOException {
FastInputReader reader = new FastInputReader(System.in);
int n = reader.nextInt(); // Number of days
int d = reader.nextInt(); // Delay allowed
int m = reader.nextInt(); // Number of events
// Use separate arrays for efficiency
int[] fr = new int[m + 2];
int[] sc = new int[m + 2];
for (int i = 1; i <= m; i++) {
fr[i] = reader.nextInt();
sc[i] = i;
}
// Add a dummy event at the end
fr[m + 1] = Integer.MAX_VALUE;
// Sort `fr` and rearrange `sc` accordingly
sortWithIndex(fr, sc, 1, m);
int l = 0, r = m;
while (r - l > 1) {
int mid = (l + r) / 2;
int p = 1;
for (int i = 1; i <= n; i++) {
if (p > m || fr[p] + d < i) {
break;
}
int cnt = 0;
while (cnt < mid && p <= m && fr[p] <= i) {
cnt++;
p++;
}
}
if (p > m) {
r = mid;
} else {
l = mid;
}
}
// Output the result
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
bw.write(r + "\n");
int p = 1;
for (int i = 1; i <= n; i++) {
int cnt = 0;
while (cnt < r && p <= m && fr[p] <= i) {
bw.write(sc[p] + " ");
cnt++;
p++;
}
bw.write("0\n");
}
bw.flush();
}
// Sort arrays `fr` and `sc` together
private static void sortWithIndex(int[] fr, int[] sc, int low, int high) {
Arrays.sort(new int[][] { fr, sc }, low, high + 1, Comparator.comparingInt(a -> a[0]));
}
static class FastInputReader {
private final DataInputStream din;
private final byte[] buffer;
private int bufferPointer, bytesRead;
public FastInputReader(InputStream in) {
din = new DataInputStream(in);
buffer = new byte[1 << 16]; // 64 KB buffer
bufferPointer = bytesRead = 0;
}
private byte read() throws IOException {
if (bufferPointer == bytesRead) {
bytesRead = din.read(buffer, 0, buffer.length);
bufferPointer = 0;
if (bytesRead == -1) return -1; // End of stream
}
return buffer[bufferPointer++];
}
public int nextInt() throws IOException {
int ret = 0;
byte c = read();
while (c <= ' ') c = read(); // Skip whitespace
boolean neg = (c == '-');
if (neg) c = read();
do {
ret = ret * 10 + c - '0';
} while ((c = read()) >= '0' && c <= '9');
if (neg) return -ret;
return ret;
}
}
}
