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 Ruby (2.7.1) (judge verdict: Accepted)

h, w = gets.split.map(&:to_i)
n = gets.to_i
as = gets.split.map(&:to_i)
table = Array.new(h, Array.new(w))
visited = Array.new(h, Array.new(w))
visited = {}

if w == 1
  dir = 'down'
else
  dir = 'right'
end
idx = 0
i = 0
j = 0
visited[0] = {}
visited[0][0] = 0

as[idx] -= 1
while (idx != n-1) || as[idx] != 0
  visited[i] ||= {}
  visited[i+1] ||= {}

  idx += 1 if as[idx] == 0
  as[idx] -= 1

  if dir == 'right'
    if j == w - 1
      i += 1
      dir = 'down'
      visited[i][j] = idx
    else
      j += 1
      visited[i][j] = idx
    end
  elsif dir == 'left'
    if j == 0
      i += 1
      dir = 'down'
      visited[i][j] = idx
    else
      j -= 1
      visited[i][j] = idx
    end
  elsif dir == 'down'
    if j == 0 && 0 == w - 1
      i += 1
      dir = 'down'
      visited[i][j] = idx
    elsif j == 0
      j += 1
      dir = 'right'
      visited[i][j] = idx
    else
      j -= 1
      dir = 'left'
      visited[i][j] = idx
    end
  end
end

h.times do |i|
  tmp = visited[i].dup
  tmp = visited[i-1].dup if tmp.nil?
  tmp2 = []
  w.times do |j|
    tmp2 << tmp[j] + 1
  end
  puts tmp2.join(' ')
end