Wire Combinations & Special Cases question from JEE Main 2022 (26 Jul, Shift 2)

A uniform heavy rod of mass $20\text{ kg}$, cross sectional area $0.4\text{ m}^2$ and length $20\text{ m}$ is hanging from a fixed support. Neglecting the lateral contraction, the elongation in the rod due to its own weight is $x \times 10^{-9}\text{ m}$. The value of $x$ is _______________.

(Given, young modulus Y = 2 $\times$ 1011 Nm−2 and g = 10 ms−2)