public int solution(String typedText) {
        int upperSum = 0;
        int lowerSum = 0;

        for (char ch : typedText.toCharArray()) {
            if (Character.isUpperCase(ch)) {
                upperSum ++;
            } else if (Character.isLowerCase(ch)) {
                lowerSum ++;
            }
        }

        return upperSum - lowerSum;
    }