K = int(raw_input())
com = [4,6,8,9,10,12]
pri = [2,3,5,7,11,13]
li = [0 for i in range(com[5] * pri[5] + 1)]
for c in com:
	for p in pri:
		li[c * p] += 1
if K > len(li) or li[K] == 0:
	print 0.0
else:
	print "{0:.15f}".format(li[K] * 1.0 /36)