import java.util.*;
class No211{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		int[] sosu = {2,3,5,7,11,13};
		int[] gose = {4,6,8,9,10,12};
		int K = sc.nextInt();
		int count = 0;
		
		for(int i=0; i<sosu.length; i++){
			for(int k=0; k<gose.length; k++){
				if(sosu[i]*gose[k] == K){
					count++;
				}
			}
		}
		
		System.out.println(String.format("%.12f",(double)count/36));
	}
}