#include <Servo.h>
Servo myservo;
int pos = 0 ;
void setup() {
  // put your setup code here, to run once:
myservo.attach(9);
}

void loop() {
  // put your main code here, to run repeatedly:
for (pos=0; pos<180; pos +=1)
{
  myservo.write(pos);
  delay(10);
}
for (pos=180; pos>=1; pos-=1)
{
  myservo.write(pos);
  delay(10);
}
}