int led=5;
int ldr=A0;
int reading=0;
void setup() {
  // put your setup code here, to run once:
pinMode(led,OUTPUT);
pinMode(ldr,INPUT);
}
void loop() {
  // put your main code here, to run repeatedly:
reading=analogRead(ldr);
if(reading>=200)
{
  digitalWrite(led,LOW);
}
else
{
  digitalWrite(led,HIGH);
}
}