! Benders example problem

A: [1 -1  5
    0  4  3
    2  0 -2
    3  0  0]     
B: [ 3  0 2
    -1  1 0
     1 -1 0
     5  5 5]
     
C: [5 4 3]
D: [2 2 3]

b: [5 7 4 -2]