int led [10] = {1, 2, 3, 4, 5} ;
int wait = 100;
void setup() {
  for(int i=0; i < 5 ;i++){
   pinMode(led [i], OUTPUT); }
}
void loop() {
  for(int i = 0 ; i < 5 ;i++){
    digitalWrite(led[i], HIGH);
    digitalWrite(led[i], LOW);
    delay(wait);

  }
for(int i = 5 ; i >= 1 ;i--) {
  digitalWrite(led[i], HIGH);
  digitalWrite(led[i], LOW);
  delay(wait);
}

  

  }