i2c Arduino display output from 4093 IC half-adder NAND

half_adder.ino

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

int carry = 2;
int sum = 5;
int carval = 0;
int sumval = 0;


LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  // Set the LCD I2C address

void setup() 
{
  Serial.begin(9600);
  // set up the LCD's number of columns and rows: 
  lcd.begin(16,2);
  pinMode(carry, INPUT);
  pinMode(sum, INPUT);
}

void loop() 
{
  sumval = digitalRead(sum);
  carval = digitalRead(carry);
  lcd.setCursor(0, 0);
  
  if ((sumval == 0) && (carval == 0))
  {
    lcd.print("Sum & carry = 0");
    lcd.setCursor(0, 1);
    lcd.print("Switches off.");
  }
  if ((sumval == 1) && (carval == 0))  
  {
    lcd.print("1 + 0 = Sum 1");
    lcd.setCursor(0, 1);
    lcd.print("One switch on.");
  }

  else if ((sumval == 0) && (carval == 1))
  {
    lcd.print("Sum 0, Carry 1");
    lcd.setCursor(0, 1);
    lcd.print("Both switches on.");
  }
  delay(500);
  lcd.clear();
}