#define SWITCH_PIN 2   // Pin connected to the switch
#define RELAY_PIN  3  // Pin connected to the relay module

void setup() {
  pinMode(SWITCH_PIN, INPUT_PULLUP);  // Set switch pin as input with internal pull-up resistor
  pinMode(RELAY_PIN, OUTPUT);         // Set relay pin as output
}

void loop() {
  int switchState = digitalRead(SWITCH_PIN);

  if (switchState == HIGH) {
    // Switch is ON, turn on LED 1 (connected to NO terminal of the relay)
    digitalWrite(RELAY_PIN, HIGH);
  } else {
    // Switch is OFF, turn on LED 2 (connected to NC terminal of the relay)
    digitalWrite(RELAY_PIN, LOW);
  }
}