! Ecker & Kupferschmid, "A branch-and-bound example in detail"
! z_min = -15; X = (2, 3, 0)
min 3 x1 - 7 x2 - 12 x3
subject to
-3 x1 + 6 x2 + 8 x3 <= 12
 6 x1 - 3 x2 + 7 x3 <= 8
-6 x1 + 3 x2 + 3 x3 <= 5
END
! Now, the first {no. of} variables are integer
GIN 3
! GIN x1
! GIN x2
! GIN x3