JEE Main 2020 — Rotational Motion Question with Solution

A circular disc of mass $\text{M}$ and radius $\text{R}$ is rotating about its axis with angular speed ${\omega }_1$. If another stationary disc having radius $\frac{\text{R}}{2}$ and same mass $\text{M}$ is dropped co-axially on to the rotating disc. Gradually both discs attain constant angular speed ${\omega }_2$. The energy lost in the process is $\text{p\%}$ of the initial energy. Value of $\mathrm{p}$ is ______