output_description: Output the greatest common divisor of _a_ and _b_.
input_description: _a_ and _b_ are given in a line sparated by a single space.
attempt: targ = [int(n) for n in input().split(" ")]
  big, small = max(targ), min(targ)
  while big % small != 0:
      disp = small
      small = big % small
      big = disp
  print(small)
  
problem_description: Greatest Common Divisor
  
  Write a program which finds the greatest common divisor of two natural numbers
  _a_ and _b_
samples: [{"input": "54 20", "output": "2"}, {"input": "147 105", "output": "21"}]