a2_2.py

def gcd(a, b):
	r = a % b
	if r == 0:
		return b
	else:
		return gcd(b, r)

print "gcd of 12 and 8 is", gcd(12, 8)
print "gcd of 10 and 5 is", gcd(10, 5)
print "gcd of 20 and 24 is", gcd(20, 24)