[13] + 0 = 13
[1, 2, 3, 5, 6, 6] + 0 = 23
[1, 3, 3, 4] + 0 = 11
[4] + 5 = 9
[12, 14] + 1 = 27
[] + 0 = 0
[4, 4, 6, 6] + 0 = 20
[5, 6, 6] + 4 = 21
[] + 0 = 0
[1, 4, 4, 5, 6] + 3 = 23