Task10_7_2

import java.util.Scanner;

class Task10_7_2 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        lettersInWord(s);
    }
    public static void lettersInWord(String s) {
        int i = 0, j = s.length() - 1, res = 0;;
        while (i < s.length()) {
            if (s.charAt(i) == s.charAt(j)) {
                res = j;
            }
            j--;
            i++;
        }
        System.out.println(s.charAt(res));
    }
}