#include <Servo.h>

Servo myservo;

void setup() {
  myservo.attach(0); // attach to pin 0
  analogReadResolution(8);
  myservo.write(180);
}

void loop() {
  if (analogRead(A0) > 180) {
    for (int pos = 180; pos >= 0; pos -= 5) { // goes from 180 degrees to 0 degrees
      myservo.write(pos);              // tell servo to go to position in variable 'pos'
      delay(15);                       // waits 15ms for the servo to reach the position
    }
    for (int pos = 0; pos <= 180; pos += 5) { // goes from 0 degrees to 180 degrees
      // in steps of 1 degree
      myservo.write(pos);              // tell servo to go to position in variable 'pos'
      delay(15);                       // waits 15ms for the servo to reach the position
    }
  }
}