#include <LCD_I2C.h>

LCD_I2C lcd(0x27, 16, 2); 
const int buttonPin = 12;  
volatile bool interruptFlag = false; 

void buttonInterrupt(){
   interruptFlag = true;
}

void setup()
{
    lcd.begin();
    lcd.backlight();

    pinMode(buttonPin, INPUT_PULLUP); 
    attachInterrupt(digitalPinToInterrupt(buttonPin), buttonInterrupt, FALLING);
}

void loop()
{
    lcd.print("Ready..03-Dindin");
    lcd.setCursor(0, 1);
    lcd.print("Press the button");
    delay(500);

    if (interruptFlag) 
    {
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("5");
        delay(500);

        lcd.setCursor(0, 1);
        lcd.print("4");
        delay(500);

        lcd.setCursor(8, 0);
        lcd.print("3");
        delay(500);

        lcd.setCursor(8, 1);
        lcd.print("2");
        delay(500);

        lcd.setCursor(15, 0);
        lcd.print("1");
        delay(500);

        lcd.setCursor(15, 1);
        lcd.print("0");
        delay(500);

        interruptFlag = false;
    }

}