A.if x>0 then y=1 else if x=0 then y=0 else y= -1
B.if x>0 then y=1 else if x<0 then y= -1 else y=0
C.if x>=0 then if x=0 then y=0 else y= -1 else y=1
D.if x<>0 then if x<0 then y= -1 else y= 1 else y=0
A.abef
B.cdef
C.abgh
D.cdgh
A.8
B.6
C.2
D.1