import java.util.Scanner;
public class Main
{   
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int a = x/10;
        int b = x%10;
        int y = 10*b+a;
        if(x>y) {
        	System.out.println(x); 
        }else {
        	System.out.println(y); 
        }
        
    }
}
/**************************************************************
	Problem: 1734
	User: admin
	Language: Java
	Result: Accepted
	Time:770 ms
	Memory:39820 kb
****************************************************************/