#include <LiquidCrystal_I2C.h>
int numbers[]={ 
  0b00111111, // 0
  0b00000110, // 1
  0b01011011, // 2
  0b01001111, // 3
  0b01100110, // 4
  0b01101101, // 5
  0b01111101, // 6
};

LiquidCrystal_I2C lcd = LiquidCrystal_I2C(0x27,20,4);
int number;
void setup() {
 Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  lcd.clear();
  lcd.setCursor(0, 0);

  lcd.println("Zadaj cislo od 0-6");
  Serial.println("Zadaj cislo od 0-6");

  for(int i;i<8;i++){
    DDRD |=1<<i;
  }

}

void loop() {

while(!Serial.available()){
number=Serial.parseInt();
}
while(Serial.available())
{
Serial.read();
}

if(number<0 && number>6){
  lcd.println("Zadaj cislo od 0 po 6");
  delay(20);
  lcd.clear();
}else{
  lcd.clear();
  lcd.println(number);
  PORTD |=numbers[number];
  delay(500);
  PORTD &=~(numbers[number]);
}

}