import std.stdio;
import std.string;
import std.conv;

void main(){
      int n = to!int(chomp(readln()));
      int[] arr = new int[157];
      real ans;

      int[] prime = [2, 3, 5, 7, 11, 13];
      int[] nonprime = [4, 6, 8, 9, 10, 12];

      foreach(ref i; prime){
            foreach(ref j; nonprime){
                  arr[i * j]++;
            }
      }

      writeln(arr[n]/36.0);

}