int led = 13;
int led1 = 12;
int led2 = 11;
int led3 = 10;
void setup() {
  // initialize the digital pin as an output.
  pinMode(led, OUTPUT);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
}

// the loop routine runs over and over again forever:
void loop() {
  digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);               // wait for a second
  digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);               // wait for a second
 digitalWrite(led1, HIGH);
 digitalWrite(led3, HIGH);// turn the LED on (HIGH is the voltage level)
  delay(1000);               // wait for a second
  digitalWrite(led1, LOW);
  digitalWrite(led3, 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               // wait for a second
}