An increase in the market price of men's haircuts, from $12 per haircut to $22 per haircut, initially causes a local barbershop to have its employees work overtime to increase the number of daily haircuts provided from 35 to 40. When the $22 market price remains unchanged for several weeks and all other things remain equal as well, the barbershop hires additional employees and provides 55 haircuts per day.

What is the long-run price elasticity of supply?