int a[4]={8,9,10,11};

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
    pinMode(4, INPUT_PULLUP);
                     //內部虛擬電阻
  for(int x=8;x<=11;x++){
    pinMode(a[x], OUTPUT);
  }

}

void loop() {
  // put your main code here, to run repeatedly:
  int value =digitalRead(4);
  
  if(value == 0){
    for(int x=0;x<=3;x++){
      for(int y=8;y<=11;y++){
        digitalWrite(a[y], HIGH);
        delay(500);
        digitalWrite(a[y], LOW);
        delay(500);
      }
    }
  }
  Serial.println(value);
}