#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    int n;
    cin >> n;
    int totalArea = n * n;
    int pinkArea = 2 * n - 1 + 3;
    double percentage = static_cast<double>(pinkArea) / totalArea * 100;
    cout << fixed << setprecision(1) << percentage << "%" << endl;
    return 0;
}

/**************************************************************
	Problem: 1345
	User: linmiaoling
	Language: C++
	Result: Wrong Answer
****************************************************************/