Appendix on android

Hello, I need an Android program that can recognize the correctness of the characters drawn. There will be 3 correct symbols. Once one of the symbols is recognized, you need to send a signal to the USB port. And you also need to be able to receive a signal from USB in order to understand that a certain symbol must be weeded out of the correct one. In short, like that. In general, you still need to be able to reset everything to the initial position on the signal from USB and make the design. We can discuss everything in detail at the meeting.
We'll agree on the price when we meet.