A coffee puzzle has left the people of Twitter scratching their heads.

Twitter user @_herbeautyxo shared the puzzle, which sees someone pouring coffee into a beaker connected to various pipes. You’re then left to guess which cup gets the coffee first.

While it might seem obvious at a glance (we presumed number four would get the coffee first), it’s not that simple. As Twitter user @HALFyute soon found out…

Still baffled? The answer is coffee cup number five.

As Twitter user @Popalop718 explains, it’s not possible for the other cups to get coffee as they are blocked off. See the red marks below.

Well there you have it. Back to work, folks.

[H/T Distractify]