왜 틀렸는지 이유를 잘 모르겠습니다..

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        Scanner sc = new Scanner(System.in);
        String s = sc.next();

        String solution = main.solution(s);
        System.out.println(solution);
    }

    public String solution(String str) {
        String answer = "";
        char[] chArr = str.toCharArray();

        if (chArr.length % 2 == 1) {
            return answer = "NO";
        }

        int lt = 0;
        int rt = chArr.length - 1;

        while (lt < rt) {
            char startWord = Character.toUpperCase(chArr[lt]);
            char lastWord = Character.toUpperCase(chArr[rt]);

            if (!(startWord == lastWord)) {
                return answer = "NO";
            }
            lt++;
            rt--;
        }
        return answer = "YES";
    }
}