Product $P$ is formed by components A and $B.$ Component $A$ is formed by parts $F$ and G$.$ Component B is formed by parts $G$ and $H.$

The inventory count is as follows.

Product P: $7$ units.

Component A: $7$ units.

Component B: $5$ units.

Part H: $6$ units.

Part F: $7$ units.

For the following bill of material, if we need to produce $27$ units of finished product $P,$ how many units of Part $F$ is required?

$\backslash$table$[[,,P,$ddots,$],[,A(2),,B(3),],[F(3),G(3),,G(3),H(4)$