import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int g = a % 10;
		int s = a / 10;
		int b = g * 10 + s;
		if(a > b){
			System.out.println(a);
		}if(a < b){
			System.out.println(b);
		}
	}

}

/**************************************************************
	Problem: 1625
	User: admin
	Language: Java
	Result: Accepted
	Time:759 ms
	Memory:40220 kb
****************************************************************/