here
"""To find the sizes of McNuggets packages"""
from math import *
number = input("Enter the number of McNuggets you want to buy :")
a=b=c=1
available = True
while available == True:
a1=number/a + 1
b1=number/b + 1
c1=number/c + 1
for a in range(0,a1):
for b in range(0,b1):
for c in range(0,c1):
if number == 6*a + 9*b + 20*c :
print "you need",a,"number of",6,"packs"
print "you need",b,"number of",9,"packs"
print "you need",c,"number of",20,"packs"
print "of McNuggets"
print "---------------------------"
available=False
print "Thank you for Buying and Have a nice day!!!"
break