#define BUTTON_PIN 2

volatile byte a = false;
byte c;

void setup() {
  for (byte b = 8; b < 14; b++) { pinMode(b, OUTPUT); }
  pinMode(BUTTON_PIN, INPUT);
  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), dd, FALLING);
}

void loop() {
  if (a) c = (c + 1) % 6; else { if (c == 0) c = 5; else c--;};
  r(8 + c);
}

void dd () {
  a = !a;
}

void r(int l) {
  digitalWrite(l, HIGH);
  delay(500);
  digitalWrite(l, LOW);
}