#include <pthread.h>
#include <cassert>

long x=0;
pthread_mutex_t m;

void* vlakno(void *)
{
  for (long i=0; i<100; i++)
    {
      pthread_mutex_lock(&m);
      x=x+1;
      pthread_mutex_unlock(&m);

    }
  pthread_exit(0);
  return 0;
}

int main()
{
  void *r;
  pthread_t p1,p2,p3;
  pthread_mutex_init (&m,0);
  pthread_create(&p1,0,vlakno,0);
  pthread_create(&p2,0,vlakno,0);
  pthread_create(&p3,0,vlakno,0);
  pthread_join(p1,&r);
  pthread_join(p2,&r);
  pthread_join(p3,&r);
  assert(x==300);
  return 0;
}