#include <LiquidCrystal_I2C.h>

#define LDR_PIN 2
#define LDR1_PIN 3

LiquidCrystal_I2C lcd(0x27, 20, 4);

void setup() {
  pinMode(LDR_PIN, INPUT);
  pinMode(LDR1_PIN, INPUT);
  lcd.init();
  lcd.backlight();
}

void loop() {
  lcd.setCursor(2, 0);
  lcd.print("Key:");
  if ((digitalRead(LDR_PIN) == LOW) && (digitalRead(LDR1_PIN) == LOW) ) {
    lcd.print("5");
  } else {
    lcd.print("Error");
  }
  delay(100);
}