output_description: 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.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      H W
      N
      a_1 a_2 ... a_N
attempt: import sys
  
  stdin = sys.stdin
  
  
  def li():
      return map(int, stdin.readline().split())
  
  
  def li_():
      return map(lambda x: int(x) - 1, stdin.readline().split())
  
  
  def lf():
      return map(float, stdin.readline().split())
  
  
  def ls():
      return stdin.readline().split()
  
  
  def ns():
      return stdin.readline().rstrip()
  
  
  def lc():
      return list(ns())
  
  
  def ni():
      return int(stdin.readline())
  
  
  def nf():
      return float(stdin.readline())
  
  
  h, w = li()
  n = ni()
  a = list(li())
  
  grid = [[0 for _ in range(w)] for _ in range(h)]
  
  k = 0
  cur = k + 1
  cnt = a[k]
  for hi in range(h):
      for wj in range(w):
          grid[hi][wj] = cur
          cnt -= 1
  
          if cnt == 0:
              k += 1
              if k == n:
                  break
  
              cur = k + 1
              cnt = a[k]
  
  for hi, row in enumerate(grid):
      if hi % 2 == 0:
          print(*row)
      else:
          row = row[::-1]
          print(*row)
  
problem_description: 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.
samples: [{"input": "2 2\n    3\n    2 1 1", "output": "1 1\n    2 3\n    \n\nBelow is an example of an invalid solution:\n\n    \n    \n    1 2\n    3 1\n    \n\nThis is because the squares painted in Color 1 are not 4-connected.\n\n* * *"}, {"input": "3 5\n    5\n    1 2 3 4 5", "output": "1 4 4 4 3\n    2 5 4 5 3\n    2 5 5 5 3\n    \n\n* * *"}, {"input": "1 1\n    1\n    1", "output": "1"}]