source_code: import java.util.Scanner;
  
  
  public class A {
  
  	static Scanner scanner = new Scanner(System.in);
  	static int s;
  
  	public static void main(String[] args) {
  		s = scanner.nextInt();
  		if (s >= 0) {
  			System.out.println(s);
  		}
  		else {
  			if (s >= -10) {
  				System.out.println(0);
  			}
  			else {
  				int ss = -s;
  				int a, b;
  				a = ss % 10;
  				b = (ss % 100) / 10;
  				if (a > b) {
  					ss = ss / 10;
  				}
  				else {
  					ss = (ss / 100) * 10 + a;
  				}
  				if (ss == 0) {
  					System.out.println(0);
  				}
  				else {
  					System.out.println("-" + ss);
  				}
  			}
  		}
  	}
  
  }
  