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;

		var r = long.MaxValue;

		for (long p = 2; p * p <= n + 1; p++)
		{
			// 3桁以上
			for (long d = p * p; d <= n + 1; d *= p)
			{
				var q = (d * p - 1) / (p - 1);
				if (n % q == 0 && 0 < n / q && n / q < p) return p;
			}

			// 2桁
			if (n % p == 0)
			{
				var q = n / p - 1;
				if (p < q) r = Math.Min(r, q);
			}
		}
		return r == long.MaxValue ? n - 1 : r;
	}
}