// include the library code:
#include <LiquidCrystal.h>

// initialize the LCD interface pins
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

// initialize button
const int button = 8;
unsigned long resetTime = 0;

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("hello, world!");
  pinMode(button, INPUT);
}

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  if (digitalRead(button) == HIGH){
    resetTime = millis();
    lcd.print("                ");
    lcd.setCursor(0,1);
  }

  unsigned long time = millis() - resetTime;
  lcd.print(time / 1000);
}