import java.util.Scanner;
import java.util.stream.IntStream;

public class Main{
	static Scanner s=new Scanner(System.in);
	static int getInt(){return Integer.parseInt(s.next());}
	static IntStream REPS(int v){return IntStream.range(0,v);}
	static IntStream REPS(int l,int r){return IntStream.rangeClosed(l,r);}
	static IntStream INS(int n) {return REPS(n).map(i->getInt());}
	static class Pair<T,U>{
		T l;U r;
		Pair(T L,U R){l=L;r=R;}
		T getL(){return l;}
		U getR(){return r;}
	}

	public static void main(String[]$){
		int k=getInt();
		double r[]=new double[13*12+1];
		int[]p={2,3,5,7,11,13},c={4,6,8,9,10,12};
		for(int i=0;i<6;++i)
			for(int j=0;j<6;++j)
				r[p[i]*c[j]]+=1.0/36;
		System.out.println(r[k]);
	}
}