public String dash(String S, int K) {
        if (S.isEmpty()) {
            return S;
        }
        int oldDash = 0;
        char[] array = S.toCharArray();
        for (int i = 0; i < array.length; i++) {
            if (array[i] == '-') {
                oldDash++;
            }
        }
        int realLen = array.length - oldDash;
        int newDash = 0;
        if (realLen % K == 0) {
            newDash = realLen / K - 1;
        } else {
            newDash = realLen / K;
        }
        char[] newArray = new char[realLen + newDash];
        int iOld = array.length - 1;
        int count = 0;
        int iNew = newArray.length - 1;
        while (iNew >= 0) {
            if (count == K) {
                newArray[iNew--] = '-';
                count = 0;
            } else if (array[iOld] != '-') {
                newArray[iNew--] = Character.toUpperCase(array[iOld--]);
                count++;
            } else {
                iOld--;
            }
        }
        return new String(newArray);
    }

    public static void main(String[] args) {
        Dash d = new Dash();
        System.out.println(d.dash("2-4A0r7-4K", 3));
    }