#include<bits/stdc++.h>
using namespace std;
#define rep(i,N) for(int (i)=0;(i) < (N); (i)++)
#define all(V) V.begin(), V.end()
using i64 = int_fast64_t;
using P = pair<i64,i64>;

int main(){
    double N;
    cin >> N;
    cout << setprecision(8) <<1.0 / N << endl;
}