How Does the Velocity of a Raft Change When Four Men Jump Off Simultaneously?

[Akash47]

Suppose four men are on a square shaped raft.All have jumped mutually perpendicularly into the river from the raft at velocity 2m/s at the same time. What will be the velocity of the center of mass of the raft?
The implied assumption is likely that the mass of the four men is same.
I think the conservation of momentum will work here.But I have drew the scenario and got that if I take two perpendicular sides as positive,then the other two sides will be negative.And also I couldn't relate the direction of the velocity of the four men.Please help me out.

 

[CWatters]

Conservation of momentum can be applied along each axis separately. So you only need to think about two men at a time.

 

[anorlunda]

What will be the velocity of the center of mass of the raft?

This could be a trick question. Velocity relative to the river or to the land?