int led1=9; 
int led2=10;
int led3=11;
int led4= 12;


void setup() {
  pinMode(led1, OUTPUT);
   pinMode(led2, OUTPUT);
   pinMode(led3, OUTPUT);
   pinMode(led4, OUTPUT);
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(led1,HIGH);
  delay(100);
   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);
}