import java.util.*;
public class closestPalindrome{
    public static boolean isPalindrome(int num){
        
        String str=String.valueOf(num);
        int left=0,right=str.length()-1;
        while (left<right){
            if(str.charAt(left)!= str.charAt(right)){
                return false;
                
            }
            left++;
            right--;
            
        }
        return true;
    }
    public static String closestPalindrome(String n){
        if(n == null||n.isEmpty()|| n.length() > 10||!n.matches("[0-9]+")){

  
}
int num=Integer.parseInt(n);
int smallerPalindrome=num-1;
int largerPalindrome=num+1;
while(!isPalindrome(smallerPalindrome)  && smallerPalindrome >0){
    smallerPalindrome--;
}
while(!isPalindrome(largerPalindrome)&& largerPalindrome >0){
    largerPalindrome++;
}
int diffSmaller =num-smallerPalindrome;
int diffLarger = largerPalindrome-num;
if (diffSmaller<=diffLarger){
    return String.valueOf(smallerPalindrome);
}else{
    return String.valueOf(largerPalindrome);
}
}
public static void main (String[]args){
    Scanner scanner=new Scanner(System.in);
    if(!sc.hasNextInt()){
        System.out.println("Invalid input");
        return;
    }
    String n=scanner.nextLine();
   
System.out.println(closestPalindrome(n));
}
}