package main

import "fmt"

var pd = [6]int{2, 3, 5, 7, 11, 13}
var cd = [6]int{4, 6, 8, 9, 10, 12}

func main() {
	var K, c int
	fmt.Scan(&K)
	for i := 0; i < len(pd); i++ {
		for j := 0; j < len(cd); j++ {
			if pd[i]*cd[j] == K {
				c++
			}
		}
	}
	fmt.Println(float64(c) / float64(36))
}