These instances are the real cost matrices of a continuous galvanizing line of a Spanish steel company. The element (i,j) of the matrix represent the cost of producing coil i right before coil j. If a value (i,j) is equal to -1, it means that the transition from coil i to coil j is forbidden. The problem consists in finding the minimun cost hamiltonian path (i.e. a minimun cost feasible sequence)