#include <LiquidCrystal_I2C.h>
#include <Servo.h>

const int ledRedPin = 5;
const int ledGreenPin = 4;
const int buttonLeftPin = 2;
const int buttonRightPin = 3;
const int servoPin = 6;

LiquidCrystal_I2C lcd(0x27, 16, 2);

Servo myServo;

int pos = 90; 

void setup() 
{
  Serial.begin(115200);
  Serial.println("Everything is okay.");

  pinMode(ledRedPin, OUTPUT);
  pinMode(ledGreenPin, OUTPUT);
  pinMode(buttonLeftPin, INPUT);
  pinMode(buttonRightPin, INPUT);

  lcd.init();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("Nothing is wrong");

  myServo.attach(servoPin);

  for(int i=0; i<10; i++)
  {
    digitalWrite(ledRedPin, HIGH);
    digitalWrite(ledGreenPin,LOW);
    delay(200);
    digitalWrite(ledRedPin, LOW);
    digitalWrite(ledGreenPin, HIGH);
    delay(200);
  }
  digitalWrite(ledGreenPin, LOW);
}

void loop() 
{
  pos -= (digitalRead(buttonLeftPin)  == LOW) ? 5 : 0;
  pos += (digitalRead(buttonRightPin) == LOW) ? 5 : 0;

  pos = constrain(pos, 0, 180);
  myServo.write(pos);

  delay(50);
}