//Lab2 . 4LED blink
#define LED1 13
#define LED2 12
#define LED3 11
#define LED4 10
void setup() {
// initialize digital pin LED_BUILTIN as an output. 
Serial.begin(9600);
  pinMode (LED1, OUTPUT);
  pinMode (LED2, OUTPUT);
  pinMode (LED3, OUTPUT);
  pinMode (LED4, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
 digitalWrite(LED1, HIGH);  // turn the LED on (HIGH is the voltage level)
 delay(1000);                    // wait for a second
 digitalWrite(LED1, LOW);   // turn the LED off by making the voltage Low
 delay(1000);                    // wait for a second
 digitalWrite(LED2, HIGH);  // turn the LED on (HIGH is the voltage level)
 delay(1000);                   // wait for a second
 digitalWrite(LED2, LOW);   // turn the LED off by making the voltage LOW
 delay(1000);                   // wait for a second
   digitalWrite(LED3, HIGH);  //1 turn the LED on (HIGH is the voltage level)
 delay(1000);                   // wait for a second
 digitalWrite(LED3, LOW); // turn the LED off by making the voltage LOW
 delay(1000);                   // wait for a second
   digitalWrite(LED4, HIGH);   // turn the LED on (HIGH is the voltage level)
 delay(1000);                   // wait for a second
 digitalWrite(LED4, LOW);   // turn the LED off by making the voltage LOW
 delay(1000);                   // wait for a second
}