int ldr = A0;
int led = 6;
int brightness=0;

void setup() {
  // put your setup code here, to run once:
pinMode(ldr, INPUT);
pinMode(led, OUTPUT);
Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
brightness=analogRead(ldr);
if(brightness<200){
  digitalWrite(led, HIGH);
} else {
  digitalWrite(led, LOW);
}
Serial.println(brightness);
}