Problem 7. Let $OP$ be the diameter of circle $\Omega$, and $\omega$ be a circle centered at point $P$ with a radius smaller than that of $\Omega$. Circles $\Omega$ and $\omega$ intersect at points $C$ and $D$. Chord $OB$ of circle $\Omega$ intersects the second circle at point $A$. Find the length of segment $AB$, if $BD \cdot BC = 5$.