int a0 = PB4;
int a1 = PB0;
int a2 = PB1;
int a3 = PB2;
int up_sw = PB5;
int down_sw = PB3;
int read_up;
int read_down;
int up;
int up_deb_count = 0;
int up_deb_count_flip = 6;
int up_deb_count_max = up_deb_count_flip * 2;
int down;
int down_deb_count = 0;
int down_deb_count_flip = 6;
int down_deb_count_max = down_deb_count_flip * 2;
int counter = 8;

void setup() 
{
  pinMode(a0, OUTPUT);
  pinMode(a1, OUTPUT);
  pinMode(a2, OUTPUT);
  pinMode(a3, OUTPUT);
  pinMode(up_sw, INPUT);
  pinMode(down_sw, INPUT);
}

void loop()
{  
  read_up = digitalRead(up_sw);
  if(read_up == 1) up_deb_count++;
  if(read_up == 0) up_deb_count--;
  if(up_deb_count > up_deb_count_flip) 
  {
    counter++;
    delay(2000);
  } 

  if(counter == 0)
  { 
    digitalWrite(a0, LOW);
    digitalWrite(a1, LOW);
    digitalWrite(a2, LOW);
    digitalWrite(a3, LOW);
  }
  if(counter == 1)
  { 
    digitalWrite(a0, HIGH);
    digitalWrite(a1, LOW);
    digitalWrite(a2, LOW);
    digitalWrite(a3, LOW);
  }
  if(counter == 2)
  { 
    digitalWrite(a0, LOW);
    digitalWrite(a1, HIGH);
    digitalWrite(a2, LOW);
    digitalWrite(a3, LOW);
  }
  if(counter == 3)
  { 
    digitalWrite(a0, HIGH);
    digitalWrite(a1, HIGH);
    digitalWrite(a2, LOW);
    digitalWrite(a3, LOW);
  }
  if(counter == 4)
  { 
    digitalWrite(a0, LOW);
    digitalWrite(a1, LOW);
    digitalWrite(a2, HIGH);
    digitalWrite(a3, LOW);
  }
  if(counter == 5)
  { 
    digitalWrite(a0, HIGH);
    digitalWrite(a1, LOW);
    digitalWrite(a2, HIGH);
    digitalWrite(a3, LOW);
  }
  if(counter == 6)
  { 
    digitalWrite(a0, LOW);
    digitalWrite(a1, HIGH);
    digitalWrite(a2, HIGH);
    digitalWrite(a3, LOW);
  }
  if(counter == 7)
  { 
    digitalWrite(a0, HIGH);
    digitalWrite(a1, HIGH);
    digitalWrite(a2, HIGH);
    digitalWrite(a3, LOW);
  }
  if(counter == 8)
  { 
    digitalWrite(a0, LOW);
    digitalWrite(a1, LOW);
    digitalWrite(a2, LOW);
    digitalWrite(a3, HIGH);
  }
  if(counter == 9)
  { 
    digitalWrite(a0, HIGH);
    digitalWrite(a1, LOW);
    digitalWrite(a2, LOW);
    digitalWrite(a3, HIGH);
  }
  if(counter == 10)
  { 
    digitalWrite(a0, LOW);
    digitalWrite(a1, HIGH);
    digitalWrite(a2, LOW);
    digitalWrite(a3, HIGH);
  }
  if(counter == 11)
  { 
    digitalWrite(a0, HIGH);
    digitalWrite(a1, HIGH);
    digitalWrite(a2, LOW);
    digitalWrite(a3, HIGH);
  }
  if(counter == 12)
  { 
    digitalWrite(a0, LOW);
    digitalWrite(a1, LOW);
    digitalWrite(a2, HIGH);
    digitalWrite(a3, HIGH);
  }
  if(counter == 13)
  { 
    digitalWrite(a0, HIGH);
    digitalWrite(a1, LOW);
    digitalWrite(a2, HIGH);
    digitalWrite(a3, HIGH);
  }
  if(counter == 14)
  { 
    digitalWrite(a0, LOW);
    digitalWrite(a1, HIGH);
    digitalWrite(a2, HIGH);
    digitalWrite(a3, HIGH);
  }
  if(counter == 15)
  { 
    digitalWrite(a0, HIGH);
    digitalWrite(a1, HIGH);
    digitalWrite(a2, HIGH);
    digitalWrite(a3, HIGH);
  }
  if(counter > 15) counter = 15;
}