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.Console;
using static System.Convert;
using static System.Math;
//using static System.Globalization.CultureInfo;

class Program
{
    struct P
    {
        public int h;
        public int w;
        public P(int h,int w)
        {
            this.h = h;
            this.w = w;
        }
    }
    static void Main(string[] args)
    {
        var hw = Array.ConvertAll(ReadLine().Split(' '), int.Parse);
        var num = ToInt32(ReadLine());
        var ar = Array.ConvertAll(ReadLine().Split(' '), int.Parse);
        
        var res = new int[hw[0]][];
        for (var i = 0; i < hw[0]; i++)
            res[i] = new int[hw[1]];
        var isY = true;
        var h = 0;
        var w = 0;
        var set = new HashSet<P>();
        var index = 0;
        var count = 0;
        var dif = 1;
        while (index != num)
        {
            res[h][w] = index + 1;
            count++;
            set.Add(new P(h, w));
            if (count == ar[index])
            {
                index++;
                count = 0;
            }
            var p = new P(h, w);
            if (isY)
                p.h += dif;
            else p.w += dif;
            if (isY && (p.h < 0 || p.h >= hw[0] || set.Contains(p)))
                isY = !isY;
            else if (!isY && (p.w < 0 || p.w >= hw[1] || set.Contains(p)))
            {
                isY = !isY;
                dif = -dif;
            }
            if (isY)
                h += dif;
            else w += dif;
        }
        WriteLine(string.Join("\n", res.Select(c => string.Join(" ", c))));
    }
    private const string ALFA = "abcdefghijklmnopqrstuvwxyz";
    private const int MOD = 1000000007;
}