int main()
{
  // set ph5 as input
  DDRH = 0x00; // 0b 0000 0000

  // activate internal pullup resistor
  PORTH = 0x20; // 0b 0010 0000
  
  // set pa0 and pa1 as outputs
  DDRA = 0x03; // 0b 0000 0011

  // set pa1 and pa3 to high level
  PORTA = 0x0a; // 0b 0000 1010

  while(1)
  {
    // test ph5
    bool btnPressed = ((PINH & 0x20) == 0x00);
        
    if(btnPressed)
    {
      // yellow on - green off
      // set pa0 and pa1 to low level
      PORTA = 0x00; // 0b 0000 0000
    }
    else
    {
      // green on - yellow off
      // set pa0 and pa1 to high level
      PORTA = 0x03; // 0b 0000 0011
    }
  }
}