package yukicoder;

import java.util.Scanner;

public class Yuki12 {
	
	public static void main( String[] args ) {
		
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
				
		for ( int i = (n - 100); i < n + 100; i++ ) {
			
			if(i<=3){
				continue;
			}
			
			if(check(i)){
				break;			
			}
		}
	}
	
	public static boolean check(int num) {
		
		for(int i=1; i <= num; i++ ) {
			
			if(i<=3){
				continue;
			}
			
			if(num%i == 0){
				System.out.println(i);
				return true;
			}
		}
		return false;
	}
}