#include <iostream>
using namespace std;

bool isClose(double x, double y) {
   if (x > y + 0.0000001) return false;
   if (y > x + 0.0000001) return false;
   return true;
}

double sqrt(double x) {
   if (x <= 0) return 0;
   double guess = x / 2;
   double ratio = x / guess;
   while (!isClose(guess, ratio)) {
      guess = (guess + ratio) / 2;
      ratio = x / guess;
   }
   return guess;
}

int main() {
   cout << "The square root of 10 is about: " << sqrt(10) << endl;
   return 0;
}