You can't concatenate the string literal and serial input with the + operator. Use 2 separate print statements.
Serial.print("Servo motor has moved ");
Serial.println(state);
The serial monitor will send characters. If you send 25, what is sent is 0x32, 0x35 and depending on the line ending setting 0x13, 0x10 may be sent. So you have to be able to receive all of the characters and then convert the characters to a number for the servo write function. See the serial input basics tutorial. or the parseInt() function.