#include <LiquidCrystal.h>

LiquidCrystal lcd(12,11,10,9,8,7); //RS,E,D4,D5,D6,D7

const int blackBtn = 5;
const int redBtn = 4;
const int greenBtn = 3;
const int blueBtn = 2;

int n = 0;

void setup() {
  lcd.begin(16, 2);
  
  pinMode(redBtn, INPUT_PULLUP);
  pinMode(greenBtn, INPUT_PULLUP);
  pinMode(blueBtn, INPUT_PULLUP); 

  displayLcd(n);
}

void loop() {
  bool redState = digitalRead(redBtn);
  bool greenState = digitalRead(greenBtn);
  bool blueState = digitalRead(blueBtn);

  if(redState == LOW){
    n++;
    displayLcd(n);
  } else if(greenState == LOW){
    n--;
    displayLcd(n);
  } else if(blueState == LOW){
    n = 0;
    displayLcd(n);
  } else if(blackState == LOW){
    displayLcd(n);
  }
}

void displayLcd(int number){
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print(number);
  delay(200);
}