public static String codeBreaker(int k, String str)
    {
        String letters = "ABCDEFGHIJKLMNOPQRSTUVDXYZ";
        int index= 0;
        String decoded = "";

        for(int i = 0; i < str.length(); i ++)
        {
            if(str.charAt(i)==(' '))
            {
                decoded += " ";
            }
            else if(letters.indexOf(str.charAt(i)) >= k)
            {
                index = letters.indexOf(str.charAt(i));
                index -= k;
                decoded += letters.charAt(index);
            }
            else
            {
                decoded += letters.charAt(letters.length()- (k - letters.indexOf(str.charAt(i))));
            }
        }

        return decoded;
    }