I cannot understand the question,

Bruce can do the following, fill jug a with 5 gallons. a = 5, b = 0 Now, he can fill jug b with 3 gallons from jug a. a = 2, b = 3 He can empty jug b and empty 2 gallons from jug a to jug b. a = 0, b = 2 Now, he can fill jug a with 5 gallons and fill jug b with 1 gallon from jug a. This results in jug a containing exactly 4 gallons of water. a = 5, b = 2

why he made it so complex, why not just pour 4 galon at the begin in a, then it is done, a = 4, b =