#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  int k;
  cin >> k;
  vector<int> a = { 2, 3, 5, 7, 11, 13 };
  vector<int> b = { 4, 6, 8, 9, 10, 12 };
  int cnt = 0;
  rep(i, 6) rep(j, 6) {
    if (a[i] * b[j] == k) cnt++;
  }
  cout << fixed << setprecision(15) << (long double) cnt / 36 << endl;
  return 0;
}