#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <set>
#include <string>
#include <vector>
#define rep(i, n) for (int i = 0; i < n; ++i)
#define FOR(i, a, b) for (int i = a; i < b + 1; ++i)
#define ll long long
#define pb(x) push_back(x)
using namespace std;

int main() {
  int k;
  cin >> k;
  int p[6] = {2, 3, 5, 7, 11, 13};
  int c[6] = {4, 6, 8, 9, 10, 12};
  int cnt = 0;
  rep(i, 6) rep(j, 6) if (p[i] * c[j] == k) cnt++;
  printf("%.13f", (double)cnt / 36);
  return 0;
}