#include <Adafruit_NeoPixel.h> 
int pin = 12;
int N_LEDS = 40;
Adafruit_NeoPixel ring = Adafruit_NeoPixel(N_LEDS, pin);

void setup(){
  ring.begin();
}

void loop(){
  for(int i = 0; i < N_LEDS; i++){
    ring.setPixelColor(i, ring.Color(0,0,0));
    ring.show();
    delay(100);
  

  if(i<10){
    ring.setPixelColor(i, ring.Color(255, 0,0));
    ring.show();
    delay(100);
  }

  else if(i>10 and i<20){
    ring.setPixelColor(i, ring.Color(0, 255, 0));
    ring.show();
    delay(100);

  }

    else if(i>20 and i<30){
    ring.setPixelColor(i, ring.Color(0, 0, 255));
    ring.show();
    delay(100);

  }

  else{
    ring.setPixelColor(i, ring.Color(255, 255, 255));
    ring.show();
    delay(100);
  }
 }
}