#include <LiquidCrystal_I2C.h>


LiquidCrystal_I2C lcd(0x27, 16, 2);

bool stl = true;
int i = 1;

void setup() {
 pinMode(3, INPUT_PULLUP);
 pinMode(2, OUTPUT);
 Serial.begin(9600);

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

void loop() {
if (digitalRead(3) == LOW && stl == true) {
    stl = false;

    lcd.clear();

    digitalWrite(2, HIGH);
    
    Serial.print("Cislo: ");
    Serial.print(i);
    Serial.print(" - ");

    lcd.print(i);
    lcd.print("-");
if (i % 2 == 0) {
    Serial.println("parne");
    lcd.print("parne");
  } else {
    Serial.println("neparne");
    lcd.print("neparne");
  }
  i++; 
  }

  if (digitalRead(3) == HIGH) {
    stl = true;
    digitalWrite(2, LOW);
  }

}