void setup() {
  pinMode(2, OUTPUT); // Set pin 2 as OUTPUT

  pinMode(3, INPUT);  // Set pin 3 as INPUT
  pinMode(13, OUTPUT); // Set pin 13 as OUTPUT (connected to the LED)
}

void loop() {
  digitalWrite(2, HIGH); // Send HIGH signal
  delay(1000);           // Wait for 1 second
  digitalWrite(2, LOW);  // Send LOW signal
  delay(1000);           // Wait for 1 second

  int signal = digitalRead(3); // Read the signal on pin 3
  if (signal == HIGH) {
    digitalWrite(13, HIGH); // Turn the LED on
  } else {
    digitalWrite(13, LOW);  // Turn the LED off
  }
}