class Solution {
    public String makeGood(String s) {
        StringBuilder sb = new StringBuilder(s);

        for (int i = 0; i < sb.length() - 1; )
        {
            int diff = sb.codePointAt(i) - sb.codePointAt(i + 1);
            if (diff == 32 || diff == -32)
            {
                sb.delete(i, i + 2);
                if (i > 0)
                {
                    i--;
                }
            }
            else
            {
                i++;
            }
        }

        return sb.toString();
    }
}