public boolean isPalindrome(int x) {
        if(x < 0) return false;

        int div = 1;
        while(x / div >= 10) div *= 10;

        while(x != 0){
            int left = x / div;
            int right = x % 10;
            if(left != right) return false;
            x = (x % div) / 10;
            div /= 100;
        }
        return true;
    }