source_code: import java.util.Scanner;
  
  
  public class A {
  
  	/**
  	 * @param args
  	 */
  	public static void main(String[] args) {
  		Account acnt = new Account();
  		acnt.solve();
  		acnt.print();
  	}
  
  }
  
  class Account {
  	
  	Account() {
  		Scanner scr = new Scanner(System.in);
  		n = scr.nextInt();
  	}
  	
  	void solve() {
  		if (n > 0) {
  			ans = n;
  		}
  		else {
  			int nn = -n;
  			int ans1 = nn/10;
  			int ans2 = nn % 10 + (nn/100)*10;
  			if (ans1 < ans2){
  				ans = -ans1;
  			}
  			else {
  				ans = -ans2;
  			}
  		}
  		
  	}
  	
  	void print(){
  		System.out.println(ans);
  	}
  	
  	int ans;
  	int n;
  }