package yukicoder312;
import java.util.Scanner;
public class Main {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		long n=sc.nextLong();
		long ans=0;
		for(long i=3;i<=n;i++){
			if(n%i==0&&i%2!=0){
				ans=i;
				break;
			}
		}
		System.out.println(ans);
		
	}
}