#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<vector<ll>> vvll;
const ll inf = 1e16;
const ll md = 1000000007;

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