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: arr = list(map(int, input().split()))
  n1 = min(arr[0], arr[1])
  n2 = max(arr[0], arr[1])
  while n1 != 0:
      temp = n2 % n1
      n2 = n1
      n1 = temp
  print(n2)
  
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"}]