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

#define LCD_ADDRESS 0x27
#define LCD_COLUMNS 16
#define LCD_ROWS 2

LiquidCrystal_I2C lcd(LCD_ADDRESS, LCD_COLUMNS, LCD_ROWS);

const byte ROWS = 4;
const byte COLS = 3;
char keys[ROWS][COLS] = {
  {'1', '2', '3'},
  {'4', '5', '6'},
  {'7', '8', '9'},
  {'C', '0', '='}
};
byte rowPins[ROWS] = {2, 4, 5, 16};
byte colPins[COLS] = {13, 14, 25};
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {
  Serial.begin(9600);

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

  lcd.setCursor(0, 0);
  lcd.print("Enter numbers:");
}

void loop() {
  char key = keypad.getKey();
  if (key) {
    static int num1 = 0, num2 = 0, num3 = 0;
    static int count = 0;

    if (key == 'C') {
      num1 = num2 = num3 = count = 0;
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Enter numbers:");
    } else if (key == '=') {
      int sum = num1 + num2 + num3;
      float average = (float)sum / 3.0;

      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Sum: ");
      lcd.print(sum);
      lcd.setCursor(0, 1);
      lcd.print("Avg: ");
      lcd.print(average, 2);
    } else {
      if (count == 0)
        num1 = num1 * 10 + (key - '0');
      else if (count == 1)
        num2 = num2 * 10 + (key - '0');
      else if (count == 2)
        num3 = num3 * 10 + (key - '0');

      count = (count + 1) % 3;

      lcd.setCursor(0, 1);
      lcd.print(num1);
      lcd.print(" ");
      lcd.print(num2);
      lcd.print(" ");
      lcd.print(num3);
    }
  }
  delay(100);
}