using System;

class I
{
	static void Main() => Console.WriteLine(Solve());
	static object Solve()
	{
		var n = long.Parse(Console.ReadLine());
		if (n <= 2) return n + 1;

		for (long p = 2; p * p <= n + 1; p++)
		{
			for (long d = p; d <= p * (n + 1); d *= p)
			{
				var q = (d - 1) / (p - 1);
				if (n % q == 0 && 0 < n / q && n / q < p) return p;
			}
		}
		return n - 1;
	}
}