#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<<"%";
}
/**************************************************************
	Problem: 1345
	User: huanglingkai
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/