const int switchA = 12;
const int switchB = 11;
const int switchC = 10;
const int LED_PIN = 9;

void setup() {
  Serial.begin(115200);
  pinMode(switchA, INPUT_PULLUP);
  pinMode(switchB, INPUT_PULLUP);
  pinMode(switchC, INPUT_PULLUP);
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  int a = !digitalRead(switchA);
  int b = !digitalRead(switchB);
  int c = !digitalRead(switchC);

  if (a || b || c)  {
    digitalWrite(LED_PIN, HIGH);
  } else {
    digitalWrite(LED_PIN, LOW);
  }
}