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 System.Text;

namespace ARC080
{
    public class D
    {
        private void Run()
        {
            var input = Console.ReadLine().Trim().Split();
            var H = int.Parse(input[0]);
            var W = int.Parse(input[1]);
            var N = int.Parse(Console.ReadLine().Trim());
            var a = Console.ReadLine().Trim().Split().Select(int.Parse).ToArray();
            var strs = a.SelectMany((x, i) => Enumerable.Repeat(i + 1, x)).ToArray();

            var result = Enumerable.Range(0, H).Select(_ => new int[W]).ToArray();
            for (int i = 0; i < H * W; i++)
            {
                var y = i / W;
                var xx = i % W;
                int x = (y % 2 == 0 ? xx : W - 1 - xx);
                result[y][x] = strs[i];
            }
            Console.WriteLine(string.Join(Environment.NewLine, result.Select(arr => string.Join(" ", arr))));
        }

        public static void Main()
        {
            var old = Console.Out;
            using (var writer = new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false })
            {
                Console.SetOut(writer);
                new D().Run();
                Console.Out.Flush();
                Console.SetOut(old);
            }
        }
    }
}