An increase in the market price of​ men's haircuts, from ​$16 per haircut to ​$26 per​ haircut, initially causes a local barbershop to have its employees work overtime to increase the number of daily haircuts provided from 40 to 45 . When the ​$26 market price remains unchanged for several weeks and all other things remain equal as​ well, the barbershop hires additional employees and provides 60 haircuts per day. What is the​ short-run price elasticity of​ supply?