#include<stdio.h>
#include<stdlib.h>

int main(int argc, char *argv[])
{
  if(argc != 2)
  {
    printf("Usage: %s fileName\n", argv[0]);
    exit(-1);
  }

  FILE *input = fopen(argv[1], "r");
  if(input == NULL)
  {
    printf("ERROR: I could not find %s\n", argv[1]);
    exit(-1);
  }

  int sum = 0;
  int temp, status;

  status = fscanf(input, "%d", &temp);
  while(status != EOF)
  {
    sum += temp;
    status = fscanf(input, "%d", &temp);
  }
  fclose(input);

  FILE *output = fopen("sum.txt", "w");
  if(output == NULL)
  {
    fprintf(stderr,"I could not open sum.txt to write, but the sum is %d\n", sum);
    exit(-1);
  }  
  else
  {
    fprintf(output, "The sum is: %d\n", sum);
    fclose(output);
  }
  return 1;
}