//注：for循环之后第三个式子总会操作一遍。

#include <iostream>

using namespace std;

int main()

{

	int n;

	while (cin >> n)

	{

		if (n == 1)

		{

			cout << 1 << endl;

		}

		else  if (n == 2)

		{

			cout << 3 << endl;

		}

		else  if (n == 3)

		{

			cout << 5 << endl;

		}

		else

		{

			int zcou = 3, znum = 6, jcou = 2;

			for (; zcou<n; znum++)

			{

				jcou = 2;

				for (int j = 2; j<(znum / 2); j++)

				{

					if (znum%j == 0)

					{

						break;

					}

					else

					{

						jcou++;

					}

				}

				if (jcou == (znum / 2))

				{

					zcou++;

				}

			}

			cout << znum -1<< endl;

		}

	}

	return 0;

}