#include<iostream>
#include<algorithm>
#include<cmath>
#include<iomanip>
#include<set>
#include<map>
#include<queue>
using namespace std;
typedef long long ll;
const int MOD=1e9+7;
int main() {
  double n;
  cin >> n;
  cout << fixed << setprecision(10) << 1/n << endl;
}