#include <iostream>
using namespace std;

int n;

int main()
{
	cin >> n;

	int c = 15;
	int m =15+ n*(n + 1) / 2;

	int l=1,r=n;
	while (r >= 1) {
		if (m - 2 * r >= 15) {
			m -= 2 * r;
		}
		else {
			r--;
		}
	}

	cout << m;

    return 0;
}