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
Pair[] a = new Pair[m + 1];
for (int i = 1; i <= m; i++) {
a[i] = new Pair(reader.nextInt(), i);
}
// Sort the array using Arrays.sort
Arrays.sort(a, 1, m + 1);
int l = 0, r = m;
// Binary search
while (r - l > 1) {
int mid = (l + r) / 2;
int p = 1;
for (int i = 1; i <= n; i++) {
if (p > m || a[p].fr + d < i) {
break;
}
int cnt = 0;
while (cnt < mid && p <= m && a[p].fr <= i) {
cnt++;
p++;
}
}
if (p > m) {
r = mid;
} else {
l = mid;
}
}
System.out.println(r);
int p = 1;
// Fast output using BufferedWriter
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
for (int i = 1; i <= n; i++) {
int cnt = 0;
while (cnt < r && p <= m && a[p].fr <= i) {
bw.write(a[p].sc + " ");
cnt++;
p++;
}
bw.write("0\n");
}
bw.flush();
}
static class Pair implements Comparable<Pair> {
int fr, sc;
Pair(int fr, int sc) {
this.fr = fr;
this.sc = sc;
}
@Override
public int compareTo(Pair other) {
return Integer.compare(this.fr, other.fr);
}
}
// Custom fast input reader
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;
}
}
}
