import random

x=random.randint(1,20)
y=random.randint(1,20)
z=random.randint(1,20)
print 'primer valor: ',x

print 'segundo valor: ',y

print 'tercer valor: ',z


def retornarmayor(x,y,z):
	if x>y and x>z:
		return x
	elif y>z:
		return y
	else:
		return z

may1=retornarmayor(x,y,z)
print 'numero mayor es: ',may1