class Solution {
    public String makeGood(String s) {
    char[] arr = s.toCharArray();
    int n = arr.length;
    LinkedList<Character> list = new LinkedList<>();
    for(int i = 0; i < n; i++){
        if(!list.isEmpty()){
            if(Math.abs(list.getLast() - arr[i]) == 'a' - 'A'){
                list.removeLast();
                continue;
            }
        }
        if(i + 1 != n && Math.abs(arr[i + 1] - arr[i]) == 'a' - 'A') i++;
        else list.add(arr[i]);
    }
    StringBuilder sb = new StringBuilder();
    while(!list.isEmpty()){
        sb.append(list.removeFirst());
    }
    return sb.toString();
}
}