int led1=13;
int led2=12;
int led3=11;
int led4=10;
void setup() {
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);
pinMode(11, OUTPUT);
pinMode(10, OUTPUT);
pinMode(9, OUTPUT);
}

void loop() {
  digitalWrite(led1, HIGH);
  delay(50);
  
  digitalWrite(led1, LOW);
  delay(100);

  digitalWrite(led2, HIGH);
  delay(100);

  digitalWrite(led2, LOW);
  delay(100);

  digitalWrite(led3, HIGH);
  delay(100);

  digitalWrite(led3, LOW);
  delay(100);

  digitalWrite(led4, HIGH);
  delay(100);

  digitalWrite(led4, LOW);
  delay(100);

  digitalWrite(led3, HIGH);
  delay(100);

  digitalWrite(led3, LOW);
  delay(100);

  digitalWrite(led2, HIGH);
  delay(100);

  digitalWrite(led2, LOW);
  delay(100);


}