#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	float f,s,g; 
	cin>>n;
	s=n*n; 
	g=n+n-1+4;
	f=g/s*100; 
	printf("%.1f",f);
	cout<<"%";	
}
/**************************************************************
	Problem: 1345
	User: sucongyi
	Language: C++
	Result: Accepted
	Time:15 ms
	Memory:2072 kb
****************************************************************/