unsigned long LED1 = 13;
unsigned long LED2 = 12;
unsigned long LED3 = 11;
unsigned long LED4 = 10;


void setup() {
  // put your setup code here, to run once:
pinMode(LED1, OUTPUT);
pinMode(LED2, OUTPUT);
pinMode(LED3, OUTPUT);
pinMode(LED4, OUTPUT);


}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(LED1, 1);
delay(50);
digitalWrite(LED1, 0);
delay(50);
digitalWrite(LED2, 1);
delay(50);
digitalWrite(LED2, 0);
delay(50);
digitalWrite(LED3, 1);
delay(50);
digitalWrite(LED3, 0);
delay(50);
digitalWrite(LED4, 1);
delay(50);
digitalWrite(LED4, 0);
delay(50);
}