#include <Servo.h>

Servo myServo;

int pos = 0;

void setup() {
  pinMode(2, INPUT);
  myServo.attach(3);
}

void loop() {
  if(digitalRead(2)==HIGH){
    for (pos = 0; pos <= 180; pos += 1){
      myServo.write(pos);
      delay(5);
    }
    for (pos = 180; pos >= 0; pos -= 1){
      myServo.write(pos);
      delay(5);
    }
  }

}