#include <Servo.h> 
 
Servo myservo;
int pos = 0;
 
void setup(){ 
  myservo.attach(9);
} 
 
void loop(){ 
  for (pos = 0; pos < 180; pos += 1){
      myservo.write(pos);
      delay(10);
  } 
  for (pos = 180; pos>=1; pos-= 1){ 
    myservo.write(pos);
    delay(10);
  } 
}