A.20 B.32 C.62 D.062
A.8 B.9 C.10 D.11
A.x.a B.x->a C.x(a) D.x{a}
A.x->name B.&x->name C.(&x)->name D.(*x)->name
A.(n+1)/2 B.n/2+1 C.n/2-1 D.n-1