week_length = 7;
nb_workers = 21;
min_daysoff = 2;
max_daysoff = 3;
min_work = 3;
max_work = 6;
nb_shifts = 3;
temp_req = [| 3, 3, 3, 3, 3, 3, 3
            | 6, 6, 6, 6, 6, 6, 6
            | 6, 6, 6, 6, 6, 6, 6 |];
shift_name = ["D", "A", "N"];
shift_start = [360, 840, 1320];
shift_length = [480, 480, 480];
shift_block_min = [2, 3, 2];
shift_block_max = [6, 4, 4];
nb_forbidden = 3;
forbidden_before = [3, 3, 2];
forbidden_after = [1, 2, 1];
forbidden_daysoff = [false, false, false];