#include<pthread.h>
#include<stdio.h>
int sum; /*This data is shared by the thread(s) */
void *runner(void *param); /* the thread */

int main(int argc, char *argv[]) 
{
pthread_t tid; /* the thread identifier */
pthread_attr_t attr; /* set of thread attributes */
if(argc != 2)
{
	fprintf(stderr,"usage: a.out <integer value>\n");
	exit(0);
}
if(atoi(argv[1]) < 0)
{
	fprintf(stderr, "%d must be >= 0 \n", atoi(argv[1]));
	exit(0);
}

/* get the default attributes */

	pthread_attr_init(&attr); 

/*create the thread */
	pthread_create(&tid,&attr,runner,argv[1]);

 /* Now wait for the thread to exit */
	pthread_join(tid,NULL);
	printf("sum = %d\n",sum);
}


/*The thread will begin control in this function */
void *runner(void *param)
{
	int upper = atoi(param);
	int i;
	sum=0;
	if(upper > 0)
	{
		for(i=1; i <= upper;i++)
		sum += i;
	}
	pthread_exit(0);
}