What do you want to count by?

import os
while True:
x = 0
y = 0
z = 0
os.system("clear")
x = input("What Would You Like To Count By?: ")
os.system("clear")
y = input("Where Would You Like To Start?: ")
os.system("clear")
z = input("Where Would You Like To End?: ")
os.system("clear")
for i in range(y,z,x):
print i
raw_input("Press Enter To Continue")