A.40~50,30~40 B.50~60,40~50 C.60~70,50~60 D.70~80,60~70
A.10 B.15 C.20 D.25
A.2~~4,9,2~~4 B.3~~5,9,3~~5 C.3~~5,10,3~~5 D.4~~6,10,4~~6