There are only 2 basic ways. In the diagrams
below, a "0" on the corner means there is NO 
lifeguard on that corner, a 1 on a corner
means there IS a lifeguard on that corner.  The 
numbers between the corners tell how many 
"non-corner" lifeguards are on that side.  In 
both cases you will notice that the sum of all 
the numbers is 14, and the sum of the numbers 
on each side is 4.

0 3 1        0 3 1            
4   2        3   3              
0 3 1        1 3 0               

Each of these can be rotated and reversed, but
these are the only two basic ways.  Edwin