source_code: import java.io.*;
  import java.util.*;
  
  public class first
  {
  	int max(int a1,int a2,int a3)
  	{
  		int max=a1;
  		if(a2>=max)
  			max=a2;
  		if(a3>=max)
  			max = a3;
  		return max;	
  	}
  	
  	public static void main(String[] args)
  	{
  		int num=0;
  		
  		Scanner sc = new Scanner(System.in);
  		num = sc.nextInt();
  		int num2 = num/10;
  		int num3 = num%10;
  		int num4 = (num2/10)*10+num3;
  		first fs = new first();
  		int result = fs.max(num,num2,num4);
  		System.out.println(result);
  	}
  }	
  