#include<bits/stdc++.h>
using namespace std;
int n,s;
int main(){
	cin>>n;
	s=4+n+(n-1);
	cout<<fixed<<setprecision(1)<<s*1.0/(n*1.0*n)*100.0<<"%";
	return 0;
}

/**************************************************************
	Problem: 1345
	User: zhangziang
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/