String alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; //26+26 symbols
        String result = "";
        k = k % 26;//correct rotate amount
        for (int i = 0; i < s.length(); i++) {
            Character currentChar = s.charAt(i);
            int index = alphabet.indexOf(currentChar); //get index of char
            if (index < 26 && index + k > 25 //correct index if it goes abroad
                    || index < 52 && index + k > 51) { //for uppercase
                index -= 26;
            }
            if (Character.isLetter(currentChar)) { //if it not a char (-' e.t.c)
                result = result + alphabet.charAt(index + k);
            } else {
                result = result + s.charAt(i);
            }
        }
        return result;