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 static System.Console;
using System.Linq;
using System.Collections.Generic;
class Program
{
    static void Main(string[] args)
    {
      string[] input = ReadLine().Split();
      int h = int.Parse(input[0]);
      int w = int.Parse(input[1]);
      int n = int.Parse(ReadLine());
      List<int> x = ReadLine().Split().ToList().ConvertAll(x=>int.Parse(x));
      List<List<int>> ans = new List<List<int>>();
      List<int> a= new List<int>();
      List<int> b = new List<int>();
      
      
      for (int i=0;i<n;i++)
      {
        for (int j=0;j<x[i];j++)
        {
          a.Add(i+1);
        }
      }
      
      for (int i=0;i<h;i++)
      {
        if (i%2==0)
        {
          WriteLine(string.Join(" ",a.GetRange(w*i, w)));
        }
        else
        {
          b = a.GetRange(w*i, w);
          b.Reverse();
          WriteLine(string.Join(" ",b));
        }
          
      }
    }
}