import java.util.Scanner; public class N211 { public static void main(String[] args) { Scanner sca = new Scanner(System.in); int K = sca.nextInt(); int[] so = { 2, 3, 5, 7, 11, 13 }; int[] go = { 4, 6, 8, 9, 10, 12 }; for (int i = 0; i < 6; i++) { for (int j = 0; j < 6; j++) { if (so[i] * go[j] == K) { System.out.println(0.0277777777777777778); return; } } } System.out.println(0); } }