#include <iostream>
#include <vector>
#include <queue>
#include <numeric>
#include <tuple>
#include <algorithm>
//#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=n;i>=0;i--)
#define FOR(i,m,n) for(int i=m;i<n;i++)
#define ALL(v) v.begin(), v.end()
#define RALL(v) v.rbegin(), v.rend()
using namespace std;
typedef long long ll;
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
//const ll INF = 1LL << 60;
//const int INF = 1001001001;

int main(void){
	int n;
	cin >> n;
	printf("%.10lf\n",1/(double)n);
	return 0;
}