/* Program to compute sum of the first N positive integers */

/* This version uses a single thread of control */

#include <stdio.h>

int main(int argc, char *argv[])
  {
    int i, limit, sum;

    /* check command line argument */
    if( argc != 2 )
      {
	fprintf(stderr, "Usage: ./summer1 value\n");
	return -1;
      }

    limit = atoi(argv[1]);
    if( limit < 0 )
      {
	fprintf(stderr, "Value must be non-negative!\n");
	return -1;
      }

    /* initialize */
    sum = 0;

    /* main loop */
    for( i = 1; i <= limit; i++ )
      {
	sum += i;
      }

    /* output the final result */
    printf("The sum of the first %d positive integers is: %d\n",
	   limit, sum);
  }