Problem:
Score : 400 points

Problem Statement

We have a grid with H rows and W columns of squares.
Snuke is painting these squares in colors 1, 2, ..., N.
Here, the following conditions should be satisfied:

For each i (1 ≤ i ≤ N), there are exactly a_i squares painted in Color i. Here, a_1 + a_2 + ... + a_N = H W.

For each i (1 ≤ i ≤ N), the squares painted in Color i are 4-connected. That is, every square painted in Color i can be reached from every square painted in Color i by repeatedly traveling to a horizontally or vertically adjacent square painted in Color i.

Find a way to paint the squares so that the conditions are satisfied.
It can be shown that a solution always exists.

Constraints

1 ≤ H, W ≤ 100

1 ≤ N ≤ H W

a_i ≥ 1

a_1 + a_2 + ... + a_N = H W

Input

Input is given from Standard Input in the following format:

H W
N
a_1 a_2 ... a_N

Output

Print one way to paint the squares that satisfies the conditions.
Output in the following format:

c_{1 1} ... c_{1 W}
:
c_{H 1} ... c_{H W}

Here, c_{i j} is the color of the square at the i-th row from the top and j-th column from the left.

Sample Input 1

2 2
3
2 1 1

Sample Output 1

1 1
2 3

Below is an example of an invalid solution:

1 2
3 1

This is because the squares painted in Color 1 are not 4-connected.

Sample Input 2

3 5
5
1 2 3 4 5

Sample Output 2

1 4 4 4 3
2 5 4 5 3
2 5 5 5 3

Sample Input 3

1 1
1
1

Sample Output 3

1

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;
import java.util.Map.Entry;
 
class Main {
	 static int mod =  (int) (Math.pow(10,9)+7);
//	 static int mod = 998244353;
   public static void main(String[] args) {
	   
       Scanner sc = new Scanner(System.in);
       int H = sc.nextInt();
       int W = sc.nextInt();
       int N = sc.nextInt();
       
       long[] a = new long[(int)N];
       long[] m= new long[H*W];
       int mcnt=0;
       for (int i=0 ; i<N; i++) {
           a[i] = sc.nextLong();
           for(int j=0;j<a[i];j++) {
        	   m[mcnt]=i+1;
        	   mcnt++;
           }
       }
 
//       String S = sc.next();
//       String T = sc.next();
//       char[] s = S.toCharArray();
//       char[] t = T.toCharArray();
       int[][] am=new int[H][W];
       int cnt=0;
       for(int i=0;i<H;i++) {
    	   if(i%2==0) {
    		   for(int j=W-1;j>=0;j--) {
    			   am[i][j]=(int) m[cnt];
    			   cnt++;
    		   }
    	   } else {
    		   for(int j=0;j<W;j++) {
    			   am[i][j]=(int) m[cnt];
    			   cnt++;
    		   }    		   
    	   }
    	   for(int j=0;j<W;j++) {
    		   System.out.print(am[i][j]);
    		   if(j!=W-1) {
    			   System.out.print(" ");
    		   }
    	   }
    	   System.out.println("");
       }
       
   }


}