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

void loop() {
  delay(100);
  digitalWrite(led1, HIGH);
  delay(100);
  digitalWrite(led1, LOW);
  digitalWrite(led2, HIGH);
  delay(100);
  digitalWrite(led2, LOW);
  digitalWrite(led3, HIGH);
  delay(100);
  digitalWrite(led3, LOW);
  digitalWrite(led4, HIGH);
  delay(100);
  digitalWrite(led4, LOW);
}