#include <Servo.h>

Servo myservo;  // create servo object to control a servo
int PIN=A0;
// twelve servo objects can be created on most boards

int pos = 0;    // variable to store the servo position

void setup() {
  pinMode(PIN, INPUT);
  digitalWrite(PIN, HIGH);
  myservo.attach(3);  // attaches the servo on pin 9 to the servo object
}

void loop() {
  if (digitalRead(PIN))
  {
    myservo.write(90);              // tell servo to go to position in variable 'pos'
    delay(15);                       // waits 15ms for the servo to reach the position
  }
  else
  {
    myservo.write(180);              // tell servo to go to position in variable 'pos'
    delay(15);                       // waits 15ms for the servo to reach the position
  }
}