The longest wavelength of light that can be used for the ionisation of lithium atom (Li) in its ground state is $x \times 10^{-8} \mathrm{~m}$.The value of x is ____________. (Nearest Integer)
(Given : Energy of the electron in the first shell of the hydrogen atom is $-2.2 \times 10^{-18} \mathrm{~J} ;$ $\mathrm{h}=6.63 \times 10^{-34} \mathrm{Js}$ and $\left.\mathrm{c}=3 \times 10^8 \mathrm{~ms}^{-1}\right)$