#include <bits/stdc++.h>
using namespace std;
#define modulo 998244353
#define mod(mod_x) ((((long long)mod_x+modulo))%modulo)
#define Inf 1000000000000000000




int main(){
	
	double N;
	cin>>N;
	
	cout<<fixed<<setprecision(15)<<1.0/N<<endl;
	
	
	
    return 0;
}