import java.util.Scanner;

public class No211 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		
		int k = sc.nextInt();
		
		int a[]={2,3,5,7,11,13};
		int b[]={4,6,8,9,10,12};
		int count=0;
		
		for(int i=0;i<6;i++){
			for(int j=0;j<6;j++){
				if(a[i]*b[j]==k)	
					count++;
			}
		}
		
		System.out.println((double)count/36);
		
	}

}