import java.util.*;

public class PalindromicPolite{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int input = sc.nextInt();
        System.out.println(counter(input));

    }

    public static boolean isPalindromic(int x){
        String s = x + "";
        for (int i = 0; i<s.length(); i++) {
            if(s.charAt(i) != s.charAt(s.length()-i-1)){
                return false;
            }
        }
        return true;
    }

    public static boolean isPolite(int x){
        for (int i = 1; i < x/2+1; i++) {
            int guess = i;
            int nextNumber = i+1;
            while (guess < x) {
                guess += nextNumber;
                if (guess == x) {
                    return true;
                }
                nextNumber++;
            }
        }
        return false;
    }
    public static int counter(int x){
        int count = 0;
        outerloop:
        for (int i = 0; true; i++) {
            count++;
            if (isPolite(i) == true && isPalindromic(i) == true && count == x) {
                break outerloop;
            }
        }
        return count;
    }

}