import math
#initialisation of variables
from math import sqrt
d=0.856 #g/ cc
N=6*10**23 # molecules
M=39.1 #g moleˆ−1
n=2
n1=4
n2=12
#CALCULATIONS
a=(n*M/(N*d))**(1/3)
d=a*10**8/ sqrt(n1)
d1=a*10**8/ sqrt(n)
d2=a*10**8/ sqrt(n2)
#RESULTS
d=d/10**6
d1=d1/10**6
d2=d2/10**6
d1=round(d1,2)
d2=round(d2,2)
print 'distance between planes =',d,'M A'
print 'distance between planes =',d1,'M A'
print 'distance between planes =',d2,'M A'