byte blueButtonState =LOW;
byte greyButtonState =LOW;
int i = 0;

void setup() {
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(13, OUTPUT);

  pinMode(3, INPUT);
  pinMode(4, INPUT);

  digitalWrite(6, HIGH);
  digitalWrite(7, HIGH);
  digitalWrite(8, LOW);
  digitalWrite(9, HIGH);
  digitalWrite(10, HIGH);
  digitalWrite(11, HIGH);
  digitalWrite(12, LOW);
  digitalWrite(13, HIGH);
}

void loop() {
  blueButtonState = digitalRead(4);
  greyButtonState = digitalRead(3);

  delay(50);

  if(blueButtonState==HIGH){
    if(i<9){
      i++; 
    }
  }
  if(greyButtonState==HIGH){
    if(i>0){
      i--;
    }
  }
  switch(i){
        case 0 :
        digitalWrite(6, HIGH);
        digitalWrite(7, HIGH);
        digitalWrite(8, LOW);
        digitalWrite(9, HIGH);
        digitalWrite(10, HIGH);
        digitalWrite(11, HIGH);
        digitalWrite(12, LOW);
        digitalWrite(13, HIGH);
        break;
        case 1:
        digitalWrite(6, LOW);
        digitalWrite(7, HIGH);
        digitalWrite(8, LOW);
        digitalWrite(9, HIGH);
        digitalWrite(10, LOW);
        digitalWrite(11, LOW);
        digitalWrite(12, LOW);
        digitalWrite(13, LOW);
        break;
        case 2:
        digitalWrite(6, HIGH);
        digitalWrite(7, HIGH);
        digitalWrite(8, LOW);
        digitalWrite(9, LOW);
        digitalWrite(10, HIGH);
        digitalWrite(11, HIGH);
        digitalWrite(12, HIGH);
        digitalWrite(13, LOW);
        break;
      }
}