#define LED_PIN A0
#define BUTTON_PIN A1

volatile bool ledState = false;

void handleInterrupt() {
  ledState = !ledState;
}

void setup() {
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), handleInterrupt, FALLING);
  
}

void loop() {
  digitalWrite(LED_PIN, ledState ? HIGH : LOW);
}