Semaphore Example: Want to know what's wrong in this code

#include<stdio.h>
#include <semaphore.h>

sem_t semA, semB;


main()
{

  sem_init(&semA, 0, 0);
  sem_init(&semB, 0, 0);

int a=0,b=0;
	while(1)
	{
		a++;
		printf("Run aaa  %d\n",a);
		sem_post(&semB);
   		sem_wait(&semA);
		printf("go to bb  %d\n",a);
		sleep(1);

	}
	while(1)
	{
		b++;
		printf("post to bbb %d\n",b);
		sem_post(&semA);
		sem_wait(&semB);
		printf("go to aaa   %d\n",b);
		sleep(1);

	}
}