  Fock states are quantized states of electromagnetic waves with diverse
applications in quantum optics and quantum communication. However, generation
of arbitrary optical Fock states still remains elusive. Majority of Fock state
generation proposals rely on precisely controlling the atom-cavity interactions
and are experimentally challenging. We propose a scheme to distill an optical
Fock state from a coherent state. A conditional phase flip (CPF) with arbitrary
phase is implemented between the atom and light. The CPF along with the unitary
rotations and measurements on the atoms enables us to distil required
Fock-state. As an example, we show the distillation of Fock-sate $\ket{100}$.
