#include <library.h>

double est_sqrt(const double N, const double g1)
{ cout << "N = " << setprecision(17) << N
       << ", g1 = " << g1 << "\n";
  if (fabs(g1*g1 - N)/N < 0.0000000000001)
    return g1;
  const double g2 = (g1 + N/g1) / 2;
  return est_sqrt(N, g2); }

void main()
{ print("y? ");
  const double y = read_double();
  print(est_sqrt(y, y/2));
  new_line(); }