#define REP(i,n) for(int i=0; i<(int)(n); i++)

#include <cstdio>
inline int getInt(){ int s; scanf("%d", &s); return s; }

#include <set>

using namespace std;

int main(){
  const int k = getInt();

  const int a[] = {2, 3, 5, 7, 11, 13};
  const int b[] = {4, 6, 8, 9, 10, 12};
  double ans = 0;
  REP(i,6) REP(j,6)
    if(a[i] * b[j] == k)
      ans += 1./36;
  printf("%.15f\n", ans);
  return 0;
}