> #include <stdio.h>
> #include<math.h>
> int main()
> {
>     double x[4],y[4];
>     while(scanf("%lf%lf%lf%lf%lf%lf%lf%lf",&x[0],&y[0],&x[1],&y[1],&x[2],&y[2],&x[3],&y[3])!=EOF)
>     {
>           int mi=-1;
>           for(int i=0;i<4;i++)
>           {
>                for(int j=i+1;j<4;j++)
>                     if(fabs(x[i]-x[j])<1e-8&&fabs(y[i]-y[j])<1e-8)
>                     {
>                          mi=i;
>                          break;
>                     }
>                if(mi!=-1) break;
>           }
>           double hx=x[0]+x[1]+x[2]+x[3],hy=y[0]+y[1]+y[2]+y[3];
>           hx-=2*x[mi],hy-=2*y[mi];
>           printf("%.3f %.3f\n",hx-x[mi],hy-y[mi]);
>     }
> }