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