A bread$-$making factory has the production process shown in the figure below. There are five operations in sequence. The product only needs to go through one of the parallel machines in each case where parallel machines exist. What is the bottleneck time of this process?

Input should be an exact number

Screen Shot $2020-11-08$ at $8\mathrm{.}27\mathrm{.}40$ PM$.$png

Operation Time

Mix $7$

Proof $12$

Bake $20$

Cut $8$

Pack $10$