using System;
using System.Collections.Generic;
using System.Linq;

namespace No192
{
	class MainClass
	{
		private static bool IsPrime(int value)
		{
			for (int i = 2; i * i <= value; i++) {
				if (value % i == 0) {
					return false;
				}
			}
			return true;
		}

		public static void Main (string[] args)
		{
			var n = Convert.ToInt32 (Console.ReadLine ());
			for(int i = Math.Max(4, n - 100);i <= n + 100;i++)
			{
				if (!IsPrime (i)) {
					Console.WriteLine (i.ToString ());
					return;
				}
			}
		}
	}
}