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# (.NET Core 3.1.201) (judge verdict: Accepted)

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

class MainClass
{
    static void Main()
    {
        var HW = ReadLine().Split().Select(int.Parse).ToArray();
        int H = HW[0];
        int W = HW[1];
        int N = int.Parse(ReadLine());
        var a = ReadLine().Split().Select(int.Parse).ToArray();

        var c = new int[H, W];
        bool f = true;
        int index = 0;
        for (int i = 0; i < H; i++)
        {
            if (f)
            {
                for (int j = 0; j < W; j++)
                {
                    if (a[index] == 0)
                    {
                        index++;
                        j--;
                        continue;
                    }
                    else
                    {
                        c[i, j] = index + 1;
                        a[index]--;
                    }
                }
            }
            else
            {
                for (int j = W - 1; j >= 0; j--)
                {
                    if (a[index] == 0)
                    {
                        index++;
                        j++;
                        continue;
                    }
                    else
                    {
                        c[i, j] = index + 1;
                        a[index]--;
                    }
                }
            }
            f = !f;
        }

        for (int i = 0; i < H; i++)
        {
            string line = "";
            for (int j = 0; j < W; j++)
            {
                line += c[i, j] + " ";
            }
            WriteLine(line.Substring(0,line.Length-1));
        }
    }
}