#define F_CPU 16000000UL // Define clock speed for potential delays (good practice)

#include <avr/io.h>
#include <avr/interrupt.h>

// Interrupt Service Routine for INT0
ISR(INT0_vect)
{
  PORTB |= (1 << PB5);   // Turn LED ON
}

// Interrupt Service Routine for INT1
ISR(INT1_vect)
{
  PORTB |= (1 << PB5);  // Turn LED OFF
}

int main(void) {
  // --- SETUP ---
  // (This code runs once at the beginning)

  // Set PB5 (pin 13) as output (LED)
  DDRB |= (1 << DDB5);

  // Set PD2 and PD3 as inputs (INT0, INT1)
  // When interrupts are enabled on these pins, they often default to input,
  // but explicitly setting them is good practice.
  DDRD &= ~((1 << DDD2) | (1 << DDD3));

  // Enable internal pull-ups (connect button to GND)
  PORTD |= (1 << PORTD2) | (1 << PORTD3);

  // Enable external interrupts INT0, INT1 in EIMSK register
  EIMSK |= (1 << INT0) | (1 << INT1);

  // Configure trigger for FALLING edge in EICRA register
  // Set ISC01 = 1, ISC00 = 0 for INT0 falling edge
  // Set ISC11 = 1, ISC10 = 0 for INT1 falling edge
  EICRA |= (1 << ISC01) | (1 << ISC11);    // Set bits 1 and 3
  EICRA &= ~((1 << ISC00) | (1 << ISC10)); // Clear bits 0 and 2

  // Enable global interrupt flag in SREG register
  sei();

  // --- LOOP ---
  // (This code runs forever after setup)
  while (1) {
    // Main loop does nothing, waits for interrupts
    // The CPU can do other tasks here or sleep
  }
}