int led1 =2;int led2 = 3;
int led3 =4;int led4 = 5;
void setup(){
  pinMode(led1,OUTPUT);
  pinMode(led2,OUTPUT);
  pinMode(led3,OUTPUT);
  pinMode(led4,OUTPUT);
}
void loop(){
  digitalWrite(led1,HIGH);
  delay(200);
  digitalWrite(led1,LOW);
  digitalWrite(led2,HIGH);
  delay(200);
  digitalWrite(led2,LOW);
  digitalWrite(led3,HIGH);
  delay(200);
  digitalWrite(led3,LOW);
  digitalWrite(led4,HIGH);
  delay(200);
  digitalWrite(led4,LOW);
  delay(500);
}