C Program to print odd and even numbers on different threads

#include 
#include 
#include 

pthread_t oddThread,evenThread;
sem_t semEven,semOdd;
int counter = -1;

void *oddFn(void *arg)
{ 
 while (counter < 15) { 
  sem_wait(&semOdd);
  printf("Counter:%d\n",++counter); 
  sem_post(&semEven);
 }
 pthread_exit(NULL);
}


void *evenFn(void *arg)
{
 while (counter < 15) { 
  sem_wait(&semEven);
  printf("Counter:%d\n",++counter); 
  sem_post(&semOdd);
 }
 pthread_exit(NULL);
}



int main(int argc, char *argv[])
{
 int ret;

 sem_init(&semEven, 0, 1); 
 sem_init(&semOdd, 0, 0);
 ret = pthread_create(&evenThread, NULL, evenFn, NULL);
 if (ret != 0) {
  perror("Error in creating Thread\n");
  exit(1);
 }

 ret = pthread_create(&oddThread, NULL, oddFn, NULL);
 if (ret != 0) {
  perror("Error in creating Thread\n");
  exit(1);
 }
 pthread_join(evenThread, NULL);
 pthread_join(oddThread, NULL);

 sem_destroy(&semEven);
 sem_destroy(&semOdd);
 pthread_exit(NULL);
}