source_code: import java.io.OutputStream;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.util.InputMismatchException;
  import java.io.InputStream;
  
  /**
   * Built using CHelper plug-in
   * Actual solution is at the top
   * @author George Marcus
   */
  public class Main {
  	public static void main(String[] args) {
  		InputStream inputStream = System.in;
  		OutputStream outputStream = System.out;
  		InputReader in = new InputReader(inputStream);
  		PrintWriter out = new PrintWriter(outputStream);
  		TaskA solver = new TaskA();
  		solver.solve(1, in, out);
  		out.close();
  	}
  }
  
  class TaskA {
      public void solve(int testNumber, InputReader in, PrintWriter out) {
          int N = in.nextInt();
          if(N >= 0)
              out.println(N);
          else {
              N = Math.abs(N);
              int v1 = - (N / 10);
              int v2 = - (N / 100 * 10 + (N % 10));
              out.println(Math.max(v1, v2));
          }
      }
  }
  
  class InputReader {
      private InputStream stream;
      private byte[] buf = new byte[1024];
      private int curChar;
      private int numChars;
  
      public InputReader(InputStream stream) {
          this.stream = stream;
      }
  
      public int read() {
          if (numChars == -1)
              throw new InputMismatchException();
          if (curChar >= numChars) {
              curChar = 0;
              try {
                  numChars = stream.read(buf);
              } catch (IOException e) {
                  throw new InputMismatchException();
              }
              if (numChars <= 0)
                  return -1;
          }
          return buf[curChar++];
      }
  
      public int nextInt() {
          return Integer.parseInt(nextString());
      }
  
      public String nextString() {
          int c = read();
          while (isSpaceChar(c))
              c = read();
          StringBuffer res = new StringBuffer();
          do {
              res.appendCodePoint(c);
              c = read();
          } while (!isSpaceChar(c));
  
          return res.toString();
      }
  
      private boolean isSpaceChar(int c) {
          return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
      }
  
      }
  
  