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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Math;

class AtCoder{
  public static void Main(){

    var input1 = Console.ReadLine().Split();
    int H = int.Parse(input1[0]);
    int W = int.Parse(input1[1]);

    int n = int.Parse(Console.ReadLine());
    var input2 = Console.ReadLine().Split();
    int[] a = new int[n];
    for (int i = 0; i < n; i++){
        a[i] = int.Parse(input2[i]);
    }

    int[,] c = new int[H,W];
    bool up = true;
    int h = 0, w =0;
    for(int i = 0; i < n; i++){
        for (int j = 0; j < a[i]; j++){
            c[h,w] = i + 1;
            if(up){
                if(w == W -1){
                    h++;
                    up = false;
                }
                else w++;
            }
            else{
                if(w == 0){
                    h++;
                    up = true;
                }
                else w--;
            }            
        }
    }

    for (int i = 0; i < H; i++){
        for (int j = 0; j < W; j++){
            Console.Write(c[i,j]);
            if(j == W-1) Console.WriteLine("");
            else Console.Write(" ");
        }
    }
  }
}