#include <Servo.h>

Servo myservo;  

int pos = 180; 
int pos1 = 0;  
int photoPin = A0;

void setup() {
myservo.attach(9);
}

void loop() {
int light = analogRead(photoPin);
if (light>500){
myservo.write(pos);             
delay(10);                       
}
else{
myservo.write(pos1);              
delay(500);                       
}
}