Hi freiend , this is a water jug problem, and avsant had given already correct anwser i want to add some thing in to it. always in water jug problem must be mind that fill one of the jug that one is middle capacity and in second step fill the lowest capacity jug then drop this value to largest and then you can see you got easyly soultion...
Might be this steps is not standarized ,but its works freiend and even i haven't fill any problem in water jug problem