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

double racine(double n);

int main()
{
  printf("%f\n", racine(4.000));

  return 0;
}

double racine(double n)
{
  double u = n;
  while (u*u-n > 0.0001)
    {
      u = ( 1 / 2 ) * (u + n / u);
    }

  return u;

}