public class NthPrime {

	public static void main(String[] args)
	{
		int counter = IO.readInt();
		counter = counter - 4;
		int number = 7;
		while (counter!=0)
		{
			number = number + 1;
			double testone = number%2;
			double testtwo = number%3;
			double testthree = number%5;
			double testfour = number%7;
				if(testone != 0 && testtwo !=0 && testthree !=0 && testfour !=0)
				{
					counter -=1;
				}
		}
		System.out.println(number);


	}
}