#-------------------------------------------------------------------------------
#  Euclid.py
#  Find the GCD of two positive integers by Euclid's algorithm
#-------------------------------------------------------------------------------

def GCD(a, b):
   """ returns the GCD of two positive integers a and b """
   if a<b:  # swap to make sure a is the larger of the two
      temp = a
      a = b
      b = temp
   r = a%b
   # print(a, b, r)
   while r>0:
      a = b
      b = r
      r = a%b
      # print( a, b, r)
   return b

# main program
print('Enter two positive integers')
a = int(input('First: '))
b = int(input('Second: '))
print( 'GCD('+str(a)+', '+str(b)+') = '+str(GCD(a, b)) )