import java.io.*; import java.util.*; class Main211 { public static void out (Object o) { System.out.println(o); } public static void main (String[] args) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); int k = Integer.parseInt(br.readLine()); int max = 200; int[] sum = new int[max]; int[] dice1 = {2,3,5,7,11,13}; int[] dice2 = {4,6,8,9,10,12}; for (int d1 : dice1) { for (int d2 : dice2) { sum[d1 * d2]++; } } out((double)sum[k] / 36); } }