int main()
{
    GPIOA->CRH = 0x44444444;
    GPIOA->CRL = 0x33333333;
    while(1)
    {
        if((GPIOA->IDR & 0x0100) == 0x0100)
            GPIOA->BSRR = 0x01;
        else
            GPIOA->BRR = 0x01;

        if((GPIOA->IDR & 0x0200) == 0x0200)
            GPIOA->BSRR = 0x02;
        else
 

            GPIOA->BRR = 0x02;

        if((GPIOA->IDR & 0x0400) == 0x0400)
            GPIOA->BSRR = 0x04;
        else
            GPIOA->BRR = 0x04;

        if((GPIOA->IDR & 0x0800) == 0x0800)
            GPIOA->BSRR = 0x08;
        else
            GPIOA->BRR = 0x08;

        if((GPIOA->
 
IDR & 0x1000) == 0x1000)
            GPIOA->BSRR = 0x10;
        else
            GPIOA->BRR = 0x10;

        if((GPIOA->IDR & 0x2000) == 0x2000)
            GPIOA->BSRR = 0x20;
        else
            GPIOA->BRR = 0x20;

        if((GPIOA->IDR & 0x4000) == 0x4000)
            GPIOA->BSRR = 0x40;
        else
 

            GPIOA->BRR = 0x40;

        if((GPIOA->IDR & 0x8000) == 0x8000)
            GPIOA->BSRR = 0x80;
        else
            GPIOA->BRR = 0x80;
    }
}