def comp_num (num1, num2, num3):
try:
if num1 > num2 and num1 > num3:
print ( "{0} is the biggest".format(num1) )
elif num2 > num1 and num2 > num3:
print ( "{0} is the biggest".format(num2))
elif num3 > num2 and num3 > num1:
print ( "{0} is the biggest".format(num3))
except ValueError:
return "Invalid input"
num_1 = int (input (" Please enter a number: "))
num_2 = int (input (" Please enter a second number: "))
num_3 = int (input (" Please enter a third number: "))
print (comp_num (num_1, num_2, num_3))