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;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace AtCoder.ABC069
{
    class Program
    {
        static void Main()
        {
            int[] inputs = Console.ReadLine().Split(' ')
                        .Select(int.Parse)
                        .ToArray();
            int H = inputs[0];
            int W = inputs[1];
            int n = int.Parse(Console.ReadLine());
            int[] a = Console.ReadLine().Split(' ')
                        .Select(int.Parse)
                        .ToArray();
            var onelinec = new List<int>();
            for (int i = 0; i < n; i++)
            {
                var tmpc = Enumerable.Repeat(i + 1, a[i]);
                onelinec.AddRange(tmpc);
            }
            Console.Error.WriteLine(string.Join(" ", onelinec));
            var c = new int[H, W];
            for (int i = 0; i < H * W; i++)
            {
                if ((i / H) % 2 == 0)
                {
                    c[i % H, i / H] = onelinec[i];
                }
                else
                {
                    c[H - 1 - (i % H), i / H] = onelinec[i];
                }
            }
            for (int i = 0; i < H; i++)
            {
                for (int j = 0; j < W; j++)
                {
                    if (j != 0) Console.Write(" ");
                    Console.Write(c[i, j]);
                }
                Console.WriteLine();
            }
        }
    }
}