#include <library.h>

double addup(int x, int lastx, double sumsofar)
{ if (x > lastx)
    return sumsofar;
  const double val = x*x - 10*x + 23;
  cout << "x = " << x << ", val = " << val << "\n";
  if (val < 0)
  { print("Error! square root of negative\n");
    return -1; }
  const double s = sqrt(val);
  return addup(x+1, lastx, sumsofar + s); }

void main()
{ print("The sum is ");
  print(addup(0, 3, 0));
  new_line(); }