int LED = 2;
int LED_2 = 6;
int LED_3 = 5;
int LED_4 = 7;

void setup() {
  // put your setup code here, to run once:
pinMode(LED, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(LED, HIGH);
delay(100);
digitalWrite(LED, LOW);
delay(100);
digitalWrite(LED_2, HIGH);
delay(100);
digitalWrite(LED_2, LOW);
delay(100);
digitalWrite(LED_3, HIGH);
delay(100);
digitalWrite(LED_3, LOW);
delay(100);
digitalWrite(LED_4, HIGH);
delay(100);
digitalWrite(LED_4, LOW);
delay(100);
}