#include <stdio.h>

#define EPS 1e-10
float my_sqrt(float x){
  float S=x, a=1,b=x;
  while(fabs(a-b)>EPS) { a=(a+b)/2; b = S / a; }
  return (a+b)/2;
}

int main()
{
  printf("%f\n", my_sqrt(1e22));
  return 0;
}

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