const uint8_t pinButton1 = 5;
const uint8_t pinButton2 = 4;
const uint8_t LED = 13;
const uint32_t timer1 = 5000;
const uint32_t timer2 = 10000;

void setup()
{
  Serial.begin( 115200 );
  pinMode( LED, OUTPUT );
  pinMode( pinButton1, INPUT_PULLUP );
  pinMode( pinButton2, INPUT_PULLUP );
}

void loop()
{
  static uint32_t timerStart = 0;
  static uint32_t timerDuration = 0;

  if ( timerDuration == 0 )
  {
    if ( digitalRead( pinButton1 ) == LOW )
    {
      timerDuration = timer1;
    }

    else if ( digitalRead( pinButton2 ) == LOW )
    {
      timerDuration = timer2;
    }

    if ( timerDuration != 0 )
    {
      digitalWrite( LED, HIGH );
      timerStart = millis();
      Serial.print( "LED on for " );
      Serial.print( timerDuration / 1000 );
      Serial.println( " seconds" );
    }
  }

  else if ( millis() - timerStart >= timerDuration )
  {
    digitalWrite( LED, LOW );
    timerDuration = 0;
    Serial.println( "LED off" );
  }
}