int entrada = A0;
int relay = 4;
int led = 3;
int LDR;
void setup() {
Serial.begin(9600);
pinMode(led, OUTPUT);
}
void loop() {
LDR = analogRead(entrada);
delay(500);
Serial.println(LDR);
if (LDR > 450){
  digitalWrite(led, HIGH);
}else{
  digitalWrite(led, LOW);
}
}