source_code: import java.io.BufferedReader;
  import java.io.FileNotFoundException;
  import java.io.FileReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.StringTokenizer;
  
  
  public class A {
  	public static void main(String[] args){
  		FastScanner sc = new FastScanner();
  		PrintWriter out = new PrintWriter(System.out);
  		String cur = sc.nextToken();
  		int first = Integer.parseInt(cur);
  		if(cur.length() > 1){
  			String second = cur.substring(0,cur.length()-1);
  			if(Character.isDigit(second.charAt(second.length()-1))){
  				first = Math.max(first, Integer.parseInt(second));
  			}
  		}
  		
  		if(cur.length() > 2){
  			String third = cur.substring(0,cur.length()-2) + cur.charAt(cur.length()-1);
  			if(Character.isDigit(cur.charAt(cur.length()-2))){
  				first = Math.max(first, Integer.parseInt(third));
  			}
  		}
  		System.out.println(first);
  		out.close();
  	}
  
  	public static class FastScanner {
  		BufferedReader br;
  		StringTokenizer st;
  
  		public FastScanner(String s) {
  			try {
  				br = new BufferedReader(new FileReader(s));
  			} catch (FileNotFoundException e) {
  				// TODO Auto-generated catch block
  				e.printStackTrace();
  			}
  		}
  
  		public FastScanner() {
  			br = new BufferedReader(new InputStreamReader(System.in));
  		}
  
  		String nextToken() {
  			while (st == null || !st.hasMoreElements()) {
  				try {
  					st = new StringTokenizer(br.readLine());
  				} catch (IOException e) {
  					// TODO Auto-generated catch block
  					e.printStackTrace();
  				}
  			}
  			return st.nextToken();
  		}
  
  		int nextInt() {
  			return Integer.parseInt(nextToken());
  		}
  
  		long nextLong() {
  			return Long.parseLong(nextToken());
  		}
  
  		double nextDouble() {
  			return Double.parseDouble(nextToken());
  		}
  	}
  }
  