xy + xm - yx - ym - mx - myxy + xm - xy - ym - mx - myxm - ym - mx - myxm - ym - mx - my-ym - my-y(m + m)-2y(m)
xy + xm - yx - ym - mx - my
xy + xm - xy - ym - mx - my
xm - ym - mx - my
xm - ym - mx - my
-ym - my
-y(m + m)
-2y(m)