def unique_file(input_filename, output_filename):

    input_file = open(input_filename, "r")
    contents = input_file.read()
    input_file.close()

    new_list = []
    words = contents.split()
    for word in words:
        if word not in words:
            new_list = new_list + (word + "\n")
            return new_list


    output_file = open(output_filename, "w")
    output_file.write(new_list)
    output_file.close()