#include <Servo.h>

int pin_servo = 9;
Servo myservo;
void setup() {
  // put your setup code here, to run once:
 myservo.attach(pin_servo);
 
}

void loop() {
  // put your main code here, to run repeatedly:
myservo.write(0);
delay(1000);  
myservo.write(180);
delay(1000);  
}