source_code: import java.util.Scanner;
  import java.io.OutputStream;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.io.InputStream;
  
  /**
   * Built using CHelper plug-in
   * Actual solution is at the top
   * @author AndrewShmig
   */
  public class Main {
  	public static void main(String[] args) {
  		InputStream inputStream = System.in;
  		OutputStream outputStream = System.out;
  		Scanner in = new Scanner(inputStream);
  		PrintWriter out = new PrintWriter(outputStream);
  		TaskA solver = new TaskA();
  		solver.solve(1, in, out);
  		out.close();
  	}
  }
  
  class TaskA {
      public void solve(int testNumber, Scanner in, PrintWriter out) {
          String n = in.nextLine();
  
          int a = Integer.parseInt(n);
          int b = Integer.parseInt(n.substring(0, n.length() - 1));
          int c = Integer.parseInt(n.substring(0, n.length() - 2) + n.charAt(n.length() - 1));
  
          out.println(Math.max(a, Math.max(b, c)));
      }
  }
  
  