//#define INPUT_1 73
//#define LED_1 RED_LED
//#define LED_2 BLUE_LED

#define INPUT_1 11
#define LED_1 33
#define LED_2 12

int state = 0;

void setup() {
  pinMode(INPUT_1, INPUT_PULLUP);
  pinMode(LED_1, OUTPUT);
  pinMode(LED_2, OUTPUT);
  
  digitalWrite(LED_1  , HIGH);
  digitalWrite(LED_2  , LOW);

  attachInterrupt(digitalPinToInterrupt(INPUT_1), change_state, FALLING);
}

void loop() {
  
  if (state == 0) {
    digitalWrite(LED_1  , HIGH);
    digitalWrite(LED_2  , LOW);
  }
  
  if (state == 1) {
    digitalWrite(LED_1  , LOW);
    digitalWrite(LED_2  , HIGH);
  }

}

void change_state() {
  state++;
  if ( state >= 2 ) {
    state = state % 2;
  }
}