0 + 1 = 1 (1 1)
1 + -1 = 0 (0 0)
69 + -42 = 27 (27 27)
42 + 69 = 111 (111 111)
-42 + 69 = 27 (27 27)
-42 + -69 = -111 (-111 -111)
256 + 512 = 768 (768 768)
123456789 + 1 = 123456790 (123456790 123456790)
2147483647 + 1 = 2147483648 (2147483648 2147483648)
-2147483648 + 1 = -2147483647 (-2147483647 -2147483647)