void setup() {
  Serial.begin(9600);                               // set the digital pin as output:
}
void loop() {
 if (Serial.available() > 0)
 {
    int x = Serial.read();         // read string until meet newline character
    
    //Serial.println(x);
    if(x=='1')
    Serial.println("Hi :)");
    else if(x=='2')
    Serial.println("Bye :(");
 }

}