#include<bits/stdc++.h>
using namespace std;
int main(){
	int a;
	float s,k=0,l;
	cin>>a;
	k=a*a;
	s=a*2+3;
	l=(s/k)*100;
	printf("%.1f",l);
	cout<<"%";
}

/**************************************************************
	Problem: 1345
	User: tonghuawei
	Language: C++
	Result: Accepted
	Time:15 ms
	Memory:2072 kb
****************************************************************/