package main

import (
	"fmt"
)

func main() {
	var k int
	fmt.Scan(&k)
	sai := make([]int, 10000)
	a := []int{2, 3, 5, 7, 11, 13}
	b := []int{4, 6, 8, 9, 10, 12}
	for _, i := range a {
		for _, j := range b {
			sai[i*j] += 1
		}
	}
	//fmt.Println(sai)
	//fmt.Println(sai[k])
	fmt.Println(float64(sai[k]) / 36)
}