#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

int a = 5;
int b = 5;

void showMath() {
  lcd.clear();

  // Row 1: the problem
  lcd.setCursor(0, 0);
  lcd.print(a);
  lcd.print(" + ");
  lcd.print(b);
  lcd.print(" = ?");

  // Row 2: the answer
  lcd.setCursor(0, 1);
  lcd.print("Answer: ");
  lcd.print(a + b);
}

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();

  showMath();

  Serial.println("Ready! Type two numbers:");
  Serial.println("Format:  a b");
  Serial.println("Example: 4 7");
}

void loop() {
  if (Serial.available()) {
    int newA = Serial.parseInt();
    int newB = Serial.parseInt();

    if (newA != 0 || newB != 0) {
      a = newA;
      b = newB;
      showMath();

      Serial.print("Updated: ");
      Serial.print(a);
      Serial.print(" + ");
      Serial.print(b);
      Serial.print(" = ");
      Serial.println(a + b);
    }
  }
}