#include <iostream>

#include <string>

#include <vector>

#include <math.h>

class Rotator {

   public:

   int c, d;

   double e, f;

   int p;

   double r, l;

   double A, B;

   //상대좌표, 기준 객체 중심점을 0, 0이라 하고 클릭된 지점

   void set(int c, int d, int x, int y){

       this->c = c;

       this->d = d;

       r = root((double)(c*c + d*d));

       double R = root(x*x + y*y);

       e = x*r/R;

       f = y*r/R;

       l = root((c-e)*(c-e)+(d-f)*(d-f));

       int k = d*e-c*f;

       if(k > 0) p = 1;

       else if(k == 0) p = 0;

       else p = -1;

       A = 1 - l*l/2/r/r;

       B = p*l/r/r*root(r*r-l*l/4);

   }

   //inline

   double root(double x){

       //다른 라이브러리 참조를 래핑한 것

       return sqrt(x);

   }

   void get(double a, double b, double& x, double& y){

       x = A*a + B*b;

       y = A*b - B*a;

   }

};

int main()

{

   Rotator test;

   test.set(1, 0, 1, 1);

   double a = -1, b = 1;

   double x, y;

   test.get(a, b, x, y);

   //std::cout << x << " " << y << std::endl;

   //std::cout << test.r;

}