char expr [] = "[[[aqqq,bqqq],cqq],[dqqq,eqqq]]"; /* success (0, (1, 16)) (1, (2, 12)) (2, (3, 7)) (3, (a, 4, 4)) (4, (q, 5, 5)) (5, (q, 6, 6)) (6, (q, 11, 11)) (7, (b, 8, 8)) (8, (q, 9, 9)) (9, (q, 10, 10)) (10, (q, 11, 11)) (11, (15, 15)) (12, (c, 13, 13)) (13, (q, 14, 14)) (14, (q, 15, 15)) (15, (26, 26)) (16, (17, 21)) (17, (d, 18, 18)) (18, (q, 19, 19)) (19, (q, 20, 20)) (20, (q, 25, 25)) (21, (e, 22, 22)) (22, (q, 23, 23)) (23, (q, 24, 24)) (24, (q, 25, 25)) (25, (26, 26)) (26, (0, 0)) (27, (0, 0)) */