The straight line joining the points
\[
(2,-2,1)
\quad\text{and}\quad
(-2,1,-1)
\]
is perpendicular to the plane
\[
\pi_1
\]
which passes through the point
\[
(1,1,1)
\]
and the equation of \(\pi_1\) is
\[
ax+by+cz+d=0.
\]
If
\[
\pi_2
\]
is the plane passing through the point
\[
(1,2,3)
\]
whose normal vector is
\[
(a,b,c),
\]
then the equation of \(\pi_2\) is