import java.util.Scanner;
public class Main{
	private static Scanner sc=new Scanner(System.in);
	public static void main(String args[])throws Exception{
		int n=sc.nextInt(),all=36,counter=0;
		int p[]={2,3,5,7,11,13};
		int np[]={4,6,8,9,10,12};
		for(int i=0;i<p.length;i++){
			for(int j=0;j<np.length;j++){
				if(p[i]*np[j]==n){
					counter++;
				}
			}
		}System.out.printf("%.18f",(double)(counter*1.0/all*1.0));
	}
}