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

sem_t S1,S2;

void* P1()
{
  int n=2;
   do {
       sem_wait(&S1);
    printf(" I1 ");
       sem_post(&S2);
    n++;
   }while (n < 10);
      pthread_exit(0); /* exit */
}

void* P2()
{
   int k=1;
   do {
       sem_wait(&S2);
            printf(" I2 ");
       sem_post(&S1);
    k++;
   }while (k < 10);
      pthread_exit(0); /* exit */
}



int main()
{
	sem_init(&S1, 0, 1);
	sem_init(&S2, 0, 0);
	pthread_t t1,t2;

	pthread_create(&t1,NULL,P1,NULL);
 
	pthread_create(&t2,NULL,P2,NULL);
	
	
	
    pthread_join(t1,NULL);
	pthread_join(t2,NULL);
	
	 
	return 0;
}