#include <stdio.h>
#include <math.h>

/*
 * A very simple program to read in three columns X, Y, Z
 * and print out them back out again
 *
 */
 
int main (void)
{
  char line [256];		/* used to buffer a whole line of input */

  double in_x, in_y, in_e;	/* input variables */
  double out_x, out_y, out_e;	/* output variables */
  double prev_x = 0, prev_y = 0, prev_e = 0; /* transitory variables */
  double integral = 0;          /* used to calculate the running int(0, sin(x)) */

  int counter = 0, rc;		/* used for debugging bad data input */

  while (fgets (line, 256, stdin)) { /* read a whole line into buffer */
    counter++;			/* increment line counter */
    rc = sscanf (line, "%lf %lf %lf", &in_x, &in_y, &in_e); /* attempt to parse variables */
    if (rc != 3) {		/* if didn't find all three protest and exit */
      fprintf (stderr, "Less than three floats on line %i:\n\"%s\"\n", counter, line);
      return 1;
    }

    out_x = in_x;		/* calculate  */
    out_y = in_y;
    out_e = in_e;

    if(counter > 1) {
      double a, b;              /* temp var */

      /* calculate the derivative */
      out_y = (in_x - prev_x) * (in_y + prev_y) / 2;
      integral += out_y;
      a = (in_x - prev_x) * in_e / 2;
      b = (-prev_x + in_x) * prev_e / 2;
      out_e = sqrt(a * a + b * b);

      printf ("%g\t%g\t%g\n", out_x, integral, out_e); /* calculate and output result */
    }

    prev_x = in_x;		/* save the previous triplet */
    prev_y = in_y;
    prev_e = in_e;
  }
  fprintf (stderr, "Processed %i lines\n", counter); /* babble some statistics */
  return 0;
}