Actualy, I want to receive a INT number from serial monitor and do calculation with this number. "int c=Serial.parseInt();" was the only way I found to do that. The main problems are if the variable 'c' carry this '1' or this '1' is sent to a bluetooth/wireless/another communication device. It can cause troubles both in calculation as communication. If there's another way (easy way) to receive a INT variable from Serial Monitor it could resolve my problem.