void blinkLED() {
  digitalWrite(23, !digitalRead(23));
  Serial.printf("[%ld]: %s\n", millis(), __func__);
}

void setup() {
  Serial.begin(115200);
  Serial.println("Lab 5.1");
  pinMode(23, OUTPUT);          // Red LED
  pinMode(22, OUTPUT);          // Blue LED
  pinMode(32, INPUT_PULLDOWN);  // Pushbutton
}

void loop() {
  delay(5000);  // 5-second freeze
  blinkLED();
  
  // Switch blue LED based on pushbutton
  digitalWrite(22, digitalRead(32));
}