int counter = 0;

int stevilke[] = {
  0b00111111, // 0
  0b00000110, // 1
  0b01011011, // 2
  0b01001111, // 3
  0b01100110, // 4
  0b01101101, // 5
  0b01111101, // 6
  0b00000111, // 7
  0b01111111, // 8
  0b01101111  // 9
};

const int btnPin1 = 8;
const int btnPin2 = 9;
const int btnPin3 = 10;
const int btnPin4 = 11;

void setup() {
  DDRD = 0b01111111; 
  pinMode(btnPin1, INPUT_PULLUP);
  pinMode(btnPin2, INPUT_PULLUP);
  pinMode(btnPin3, INPUT_PULLUP);
  pinMode(btnPin4, INPUT_PULLUP);
}

void loop() {
  int btnState = (digitalRead(btnPin1) << 3) | (digitalRead(btnPin2) << 2) | (digitalRead(btnPin3) << 1) | digitalRead(btnPin4);

  switch(btnState){
    case 0b00001110:
      counter++;
      delay(200);
      break;
      
    case 0b00001101: 
      counter--;
      delay(200);
      break;
      
    case 0b00001011:
      counter = 0;
      delay(200);
      break;
      
    case 0b00000111: 
      randomSeed(analogRead(A0));
      counter = random(0, 10);
      delay(200);
      break;
  }

  if (counter < 0){
    counter = 9;
  } else if(counter > 9){
    counter = 0;
  };

  int izpis = stevilke[counter];
  PORTD = (PORTD & 0b10000000) | izpis;
}