import java.util.*;

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