#define L1 PB5
#define L2 PB6
#define L3 PB7
#define L4 PB8

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(1000);
  digitalWrite(L1, LOW);
  digitalWrite(L2, HIGH);
  digitalWrite(L3, LOW);
  digitalWrite(L4, LOW);
  delay(1000);
  digitalWrite(L1, LOW);
  digitalWrite(L2, LOW);
  digitalWrite(L3, HIGH);
  digitalWrite(L4, LOW);
  delay(1000);
  digitalWrite(L1, LOW);
  digitalWrite(L2, LOW);
  digitalWrite(L3, LOW);
  digitalWrite(L4, HIGH);
  delay(1000);
}