output_description: If the conditions cannot be satisfied by writing 0 or 1 in each of the
  squares, print -1.
  
  If the conditions can be satisfied, print one way to fill the squares so that
  the conditions are satisfied, in the following format:
  
      
      
      s_{11}s_{12}\cdots s_{1W}
      s_{21}s_{22}\cdots s_{2W}
      \vdots
      s_{H1}s_{H2}\cdots s_{HW}
      
  
  Here s_{ij} is the digit written in the square at the i-th row from the top
  and the j-th column from the left in the grid.
  
  If multiple solutions exist, printing any of them will be accepted.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      H W A B
attempt: from fractions import gcd
  
  
  def solve(h, w, a, b):
      ans = []
  
      if h == 1:
          ans = ["0" * a + "1" * (w - a)]
          return ans
      loop = w // gcd(w, a)
      val = loop * a // w
  
      base = "0" * a + "1" * (w - a)
      not_base = "1" * a + "0" * (w - a)
      loop_str = []
      for i in range(loop):
          shift = (w // loop) * i
          loop_str.append(base[shift:] + base[:shift])
      fill_str = [base, not_base]
  
      for i in range(h // loop + 1):
          if (h - loop * i) % 2 == 1:
              continue
          fill = (h - loop * i) // 2
          ret = i * val + fill
          if ret == b:
              ans += loop_str * i
              ans += fill_str * fill
              return ans
      return None
  
  
  h, w, a, b = [int(item) for item in input().split()]
  
  ans = solve(h, w, a, b)
  if ans:
      for line in ans:
          print(line)
      exit()
  ans = solve(w, h, b, a)
  if ans:
      nans = ""
      for j in range(h):
          for i in range(w):
              nans += ans[i][j]
          nans += "\n"
      print(nans, end="")
      exit()
  print("No")
  
problem_description: Statement
  
  We have a square grid with H rows and W columns. Snuke wants to write 0 or 1
  in each of the squares. Here, all of the following conditions have to be
  satisfied:
  
    * For every row, the smaller of the following is A: the number of 0s contained in the row, and the number of 1s contained in the row. (If these two numbers are equal, “the smaller” should be read as “either”.)
    * For every column, the smaller of the following is B: the number of 0s contained in the column, and the number of 1s contained in the column.
  
  Determine if these conditions can be satisfied by writing 0 or 1 in each of
  the squares. If the answer is yes, show one way to fill the squares so that
  the conditions are satisfied.
samples: [{"input": "3 3 1 1", "output": "100\n    010\n    001\n    \n\nEvery row contains two 0s and one 1, so the first condition is satisfied.\nAlso, every column contains two 0s and one 1, so the second condition is\nsatisfied.\n\n* * *"}, {"input": "1 5 2 0", "output": "01010"}]