source_code: import static java.lang.Math.*;
  import static java.util.Arrays.*;
  import static java.util.Collections.*;
  import java.io.*;
  import java.math.*;
  import java.util.*;
  
  @SuppressWarnings("unused")
  public class A {
  	public static void main(String[] args) throws Exception {
  		Scanner in = new Scanner(System.in);
  		int n = in.nextInt();
  		TreeSet<Integer> set = new TreeSet<Integer>();
  		set.add(n);
  		try {
  			String s = Integer.toString(n);
  			s = s.substring(0, s.length() - 1);
  			set.add(Integer.parseInt(s));
  		} catch (Exception e) {
  		}
  		try {
  			String s = Integer.toString(n);
  			s = s.substring(0, s.length() - 2) + s.charAt(s.length() - 1);
  			set.add(Integer.parseInt(s));
  		} catch (Exception e) {
  		}
  		System.out.println(max(set));
  	}
  }
  