PROCEDURE gline(x1,y1,x2,y2 :INTEGER);
  BEGIN
    LINE(x1,y1,x2,y2)
  END;

PROCEDURE cadd(VAR c1,c2,c3:complex);
  BEGIN
    c3.re := c1.re+c2.re;
    c3.im := c1.im+c2.im
  END;

PROCEDURE csub(VAR c1,c2,c3:complex);
  BEGIN
    c3.re := c1.re-c2.re;
    c3.im := c1.im-c2.im
  END;

PROCEDURE cmul(VAR c1,c2,c3:complex);
  BEGIN
    c3.re := c1.re*c2.re-c1.im*c2.im;
    c3.im := c1.re*c2.im+c1.im*c2.re
  END;

PROCEDURE set_complex(xre,xim:REAL; VAR c:complex);
 BEGIN
    c.re := xre;
    c.im := xim
  END;

PROCEDURE cline(c1,c2 :complex);
  BEGIN
    gline(ROUND(c1.re*1000),ROUND(c1.im*1000),
          ROUND(c2.re*1000),ROUND(c2.im*1000))
  END;

PROCEDURE ftree(c1,c2,f0,f1 :complex; n :INTEGER);
  VAR
    z,z0,z1 :complex;
  BEGIN
    IF 0 < n THEN
      BEGIN
        cline(c1,c2);
        csub(c2,c1,z);
        cmul(z,f0,z0);
        cmul(z,f1,z1);
        cadd(c1,z0,z0);
        cadd(c1,z1,z1);
        ftree(c2,z0,f0,f1,n - 1);
        ftree(c2,z1,f0,f1,n - 1);
      END
  END;