#include <iostream>
#include <algorithm>
#include <string>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
#define SQR(X) ((X)*(X))

typedef long long ll;
typedef unsigned long long ull;
typedef long double lb;
/* ここからが本編 */

int main(void)
{
   int i,j;
   int k;
   int a[6] = {2,3,5,7,11,13};
   int b[6] = {4,6,8,9,10,12};
   int cnt = 0;
   cin >> k;
   rep(i,6) {
      rep(j,6) {
         if(k == a[i]*b[j]) cnt++;
      }
   }
   printf("%.14lf\n",cnt/36.0);
   return 0;
}