A={a,b}. Удвоить слово P:P->PP. Пример:abb->abbabb. Каретка-над крайним левым символом

hi, students, how are you doing? how did you spend your summer vacation? I think you know me . I taught you a lesson a year ago, if you forgot my name is Gulnur. I know that it will not be easy to learn online, but we must be patient. I wish you success this academic year

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