import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		sc.close();

		if (n <= 3) {
			System.out.println(n);
		} else {
			long n2 = n - 3;
			long ans = n2 * 5 + 3;
			System.out.println(ans);
		}
	}
}