#include<Servo.h>
Servo servo;

int ldr1 = A0;
int ldr2 = A1;
int motor = 13;
int pos = 90;

void setup()
{
  Serial.begin(9600);
  pinMode(ldr1, INPUT);
  pinMode(ldr2, INPUT);
  servo.attach(motor);
  servo.write(90);
}

void loop()
{
  int val1 = analogRead(ldr1);
  int val2 = analogRead(ldr2);
  
  Serial.print("The value of ldr1 is ");
  Serial.println(val1);
  Serial.print("The value of ldr2 is ");
  Serial.println(val2);
  
  if (abs(val1 - val2) > 20)
  {
    if(val2 > val1)
    {
      servo.write(--pos);
    }
    if(val1 > val2)
    {
      servo.write(++pos);
    }
  }
  else
  {
    servo.write(90);
  }
}