func main()
	var K: int :: cui@input().toInt(&)
	var arr1: []int :: [2, 3, 5, 7, 11, 13]
	var arr2: []int :: [4, 6, 8, 9, 10, 12]
	var ans: int
	for i(0, 5)
		for j(0, 5)
			if(arr1[i] * arr2[j] = K)
				do ans :+ 1
			end if
		end for
	end for
	do cui@print("\{(ans $ float / 36.0).toStrFmt(".15f")}\n")
end func