int ledPin12 = 12;                 // LED connected to digital pin 12
int ledPin11 = 11;                 // LED connected to digital pin 11
int ledPin10 = 10;                 // LED connected to digital pin 10
int ledPin9 = 9;                 // LED connected to digital pin 9



void setup()
{
  pinMode(ledPin12, OUTPUT);      // sets the digital pin as output
  pinMode(ledPin11, OUTPUT);      // sets the digital pin as output
  pinMode(ledPin10, OUTPUT);      // sets the digital pin as output
  pinMode(ledPin9, OUTPUT);      // sets the digital pin as output
}

void loop()
{
  digitalWrite(ledPin12, HIGH);   // sets the LED on
  delay(10);                  // waits for a second
  digitalWrite(ledPin12, LOW);    // sets the LED off
  delay(10);                  // waits for a second

  digitalWrite(ledPin11, HIGH);   // sets the LED on
  delay(10);                  // waits for a second
  digitalWrite(ledPin11, LOW);    // sets the LED off
  delay(10);                  // waits for a second

  digitalWrite(ledPin10, HIGH);   // sets the LED on
  delay(10);                  // waits for a second
  digitalWrite(ledPin10, LOW);    // sets the LED off
  delay(10);                  // waits for a second

  digitalWrite(ledPin9, HIGH);   // sets the LED on
  delay(10);                  // waits for a second
  digitalWrite(ledPin9, LOW);    // sets the LED off
  delay(10);                  // waits for a second

  delay(100);

}