#coding:utf-8

prime=[2,3,5,7,11,13]
composit=[4,6,8,9,10,12]

K=input()

n=[i*u for i in prime for u in composit]

if K in n:
	print 0.0277777777777777778*n.count(K)
else:
	print 0.00000000000000000