#define L1 9
#define L2 10
#define L3 11
#define L4 12

void setup() {
  pinMode(L1, OUTPUT);
  pinMode(L2, OUTPUT);
  pinMode(L3, OUTPUT);
  pinMode(L4, OUTPUT);
}

void loop() {
  digitalWrite(L1, HIGH);
  digitalWrite(L2, LOW);
  digitalWrite(L3, LOW);
  digitalWrite(L4, LOW);
  delay(1002);
  digitalWrite(L1, LOW);
  digitalWrite(L2, HIGH);
  digitalWrite(L3, LOW);
  digitalWrite(L4, LOW);
  delay(2002);
  digitalWrite(L1, LOW);
  digitalWrite(L2, LOW);
  digitalWrite(L3, HIGH);
  digitalWrite(L4, LOW);
  delay(3002);
  digitalWrite(L1, LOW);
  digitalWrite(L2, LOW);
  digitalWrite(L3, LOW);
  digitalWrite(L4, HIGH);
  delay(4002);
}