int led1 = 12;
int led2= 13;

void setup() {
  // Set the LED pins as output
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
 
}

void loop() {
  digitalWrite(led1, HIGH); 
  delay(1000);               
  digitalWrite(led1, LOW);  

  digitalWrite(led2, HIGH); 
  delay(1000);
  digitalWrite(led2, LOW);  

 
}