AMC 8 2026 (Problem 1)

What is the value of the following expression?1+23+4+56+7+89+10+11121+2-3+4+5-6+7+8-9+10+11-12
(A)  18\text{(A)}\;18(B)  21\text{(B)}\;21(C)  24\text{(C)}\;24(D)  27\text{(D)}\;27(E)  30\text{(E)}\;30