import java.util.*;

public class Main {
	public static void main(String[] args) {

		int o,p,q;
		int a = 0, b = 0,c=0;
		
		Scanner sc  = new Scanner(System.in);
//		int[] test  = new int[100000];
//    	int[] test2 = new int[1000];
		
	//  String str1 = sc.next();
	  long	t = Long.parseLong(sc.next());

		for(long i= 3 ;t > i ; i++){
			
			
			if(t%i==0){
			System.out.println(i);
				break;
				
			}
			
			
			
		}


	//  String str2 = sc.next();
	
	 /*   
	  int	s = Integer.parseInt(sc.next());
	  int	t = Integer.parseInt(sc.next());
	  int	u = Integer.parseInt(sc.next());
		*/

		
   /*
      int d = 0;
    　　　　while(true){
		
       int	v = Integer.parseInt(sc.next());
       test2[d] = v ;
     	d++;
		}
		
		*/
/*
	  for(int i=0;i<c1.length;i++){
			if(c1[i]!=c2[i]){
				System.out.println("NO");
				return;
			}
		}
		*/

		  System.out.println();
	}
}