blink X times for Y ms with X and Y sent over serial

controlled_blink.ino

int led_pin = LED_BUILTIN;

void setup() {
  pinMode(led_pin, OUTPUT);
  digitalWrite(led_pin, LOW);

  Serial.begin(115200);
  Serial.println("hello!");
}

// parse messages such as "3;100" (3 blinks of 100ms)...

void loop() {
  if (Serial.available() > 0) { // check if we received something
    Serial.println(Serial.read());
        
    int X = Serial.parseInt(); // number of blinks
    Serial.println(X);

    int Y = Serial.parseInt(); // duration of blinks
    Serial.println(Y);

    for (int i = 0; i < X; i++) { // loop Y times
      digitalWrite(led_pin, HIGH);
      delay(Y);
      
      digitalWrite(led_pin, LOW);
      delay(Y);
    }
    
  }
}