--------------------- 1 a a --------------------- 1/2 b b b b --------------------- 1/4 c c c c c2 c2 c2 c2 --------------------- start C C' B A A' B' C2 C2'
--------------------- 1 a a --------------------- 1/2 b b b b --------------------- 1/4 c c c c c2 c2 c2 c2 --------------------- start C C' B A A' B' C2 C2'