#include<stdio.h>
#include<math.h>
int main(int argc, char *argv[])
{
  FILE *input;
  float x, y, sumx, sumy, avex, avey, sumx_sqrd, sumy_sqrd, xmax, ymax;
  int count;
  if (argc == 1)
     {
     fprintf(stderr, "You must supply a file name.\n");
     return 1;
     }
  input = fopen(argv[1], "r");
  if (input == NULL)
     {
     fprintf(stderr, "Error opening file \"%s\".\n", argv[1]);
     return 1;
     }
  sumx = 0.0;
  sumy = 0.0;
  sumx_sqrd = 0.0;
  sumy_sqrd = 0.0;
  count = 0;
  while (fscanf(input, "%f\t%f", &x, &y) != EOF)
        {
        count++;
        sumx += x;
        sumy += y;
        sumx_sqrd += x * x;
        sumy_sqrd += y * y;
        }
 
  fclose(input);
  avex = sumx/count;
  avey = sumy/count;
  printf("Average of x = %f\n", avex);
  printf("Standard deviation of x = %f\n", sqrt(sumy_sqrd/count - avex * avex));
  printf("\n");
  printf("Average of y = %f\n", avey);
  printf("Standard deviation of y = %f\n", sqrt(sumy_sqrd/count - avey * avey));
  printf("\n");
  printf("The maximum x value is %f\n", );
  printf("The maximum y value is %f\n", );
  printf("\n");
  printf("The number of data sets is %d\n", count);
  return 0;
}