#include <Servo.h>

int SRV = 9;
int count = 0;

Servo myservo;

void setup(){
  Serial.begin(9600);
  pinMode(SRV, OUTPUT);
}

void loop(){
  count++;
  Serial.write(count);
  while(Serial.available()){
    if((count % 2) == 1){ 
    myservo.attach(9);
    myservo.write(0);
    delay(500);
    myservo.write(180);
    delay(500);
  }
}
}