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
   */
  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) {
          int balance = in.nextInt();
          if (balance >= 0) {
              out.println(balance);
              return;
          }
  
          balance = -balance;
          int a = balance / 100;
  
          int b = Math.min(balance % 10, (balance / 10) % 10);
  
          balance = -(a * 10 + b);
  
          out.println(balance);
      }
  }
  
  