int led1=6;
int led2=5;
int led3=3;
void setup() {
  pinMode(6, OUTPUT);
 pinMode(5, OUTPUT);
 pinMode(3, OUTPUT);
}

void loop() {
 digitalWrite(led1, HIGH);
 delay(1000);
 digitalWrite(led1, LOW);
 digitalWrite(led2, HIGH);
 delay(1000);
 digitalWrite(led2, LOW);
 digitalWrite(led3, HIGH);
 delay(1000);
 digitalWrite(led3, LOW);
 digitalWrite(led2, HIGH);
 delay(1000);
 digitalWrite(led2, LOW);
 digitalWrite(led1, HIGH);
 digitalWrite(led2, HIGH);
 digitalWrite(led3, HIGH);

}