#include <pthread.h>
#include <unistd.h>
static void *th(void *v)
{
sleep(1);
pthread_exit(0);
}
int main()
{
pthread_t a;
pthread_create(&a, NULL, th, NULL);
pthread_create(&a, NULL, th, NULL);
pthread_create(&a, NULL, th, NULL);
pthread_create(&a, NULL, th, NULL);
pthread_exit(0);
}