week_length = 7;
nb_workers = 30;
min_daysoff = 1;
max_daysoff = 4;
min_work = 3;
max_work = 7;
nb_shifts = 3;
temp_req = [| 8, 8, 7, 7, 7, 5, 5
            | 8, 7, 7, 7, 7, 0, 0
            | 9, 9, 9, 9, 9, 3, 3 |];
shift_name = ["D", "A", "N"];
shift_start = [360, 840, 1320];
shift_length = [480, 480, 480];
shift_block_min = [2, 2, 3];
shift_block_max = [5, 5, 4];
nb_forbidden = 7;
forbidden_before = [3, 3, 2, 3, 2, 3, 3];
forbidden_after = [1, 2, 1, 3, 1, 2, 1];
forbidden_daysoff = [false, false, false, true, true, true, true];