import java.util.*;
//import java.text.*;

public class Exercise77{
  public static void main (String[] args){

    //DecimalFormat df = new DecimalFormat("#.############");
    Scanner sc = new Scanner(System.in);

    double n = sc.nextDouble();

    double[] pDice = new double[]{2, 3, 5, 7, 11, 13};
    double[] cDice = new double[]{4, 6, 8, 9, 10, 12};

    double count = 0;

    for (int i = 0; i < pDice.length; i++){
      if (n % pDice[i] != 0){
        continue;
      }
      double devided = n / pDice[i];
      for (int j = 0; j < cDice.length; j++){
        if (devided == cDice[j]){
          count++;
        }else{
        }
      }
    }
    System.out.println(count / (double)(pDice.length * cDice.length));
  }
}