A thin uniform circular disc of mass 'M' an radius 'R' is rotating with angular velocity 'ω' in a

A thin uniform circular disc of mass 'M' and
radius 'R' is rotating with angular velocity 'ω',
in a horizontal plane about an axis passing
through its centre and perpendicular to its plane.
Another disc of same radius but of mass (M/2) is placed gently on the first disc co-axially. The new angular velocity will be [2023]