#include <Arduino.h>
const int ledPins[] = {19, 18, 5, 17}; 
const int buttonPin = 0;
int count = 3; 
bool ledCounterOn = false;

void setup() {
  
  for (int i = 0; i < 4; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
  
  
  pinMode(buttonPin, INPUT_PULLUP);
}

void loop() {
  
  int buttonState = digitalRead(buttonPin);
  if (buttonState == LOW) {
    ledCounterOn = !ledCounterOn;
    delay(50); 
  }
  
  if (ledCounterOn) {
    count--;
    updateLEDs();
    delay(500); // Delay between each LED
  }
}

void updateLEDs() {
  
  if (count == -1) {
    count = 3;
  }
  
  
  for (int i = 0; i < 4; i++) {
    digitalWrite(ledPins[i], LOW);
  }
   digitalWrite(ledPins[count], HIGH);
}