#include <stdint.h>

int main(){
  uint32_t *RCC_IOPENR = (uint32_t *)0x40021034;
  uint32_t *GPIOAMODER = (uint32_t *)0x50000000;

  *RCC_IOPENR= 1;
  *GPIOAMODER=0x00000400;
  while(1);
  return 0;
}