#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,r;
	float s,p;
	cin>>n;
	r=2*n+3;
	s=n*n;
	p=(r/s)*100;
	cout<<fixed<<setprecision(1)<<p<<"%"<<endl;
	return 0;
}
/**************************************************************
	Problem: 1345
	User: xiaojingxuan
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/