import java.util.*;
public class Main{
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
while(sc.hasNext()){
int n=sc.nextInt();
if(n==1 || n==2){
System.out.println(-1);
}
else if(n%4==3 || n%4==1){
System.out.println(2);
}
else if(n%4==0){
System.out.println(3);
}
else if(n%4==2){
System.out.println(4);
}
}
}
}