int pinLed=4;
int pinSenLuz=13;
void setup() {
  Serial.begin(9600);
  pinMode(pinLed, OUTPUT);
  pinMode(pinSenLuz, INPUT_PULLUP);
}
void loop() {
  int valor;
  valor=digitalRead(pinSenLuz);
  if(valor== HIGH)
    digitalWrite(pinLed, HIGH);
  else
    digitalWrite(pinLed, LOW);
}