Maestro n° 087 : Page 81 - Gr 78
L1C9 -9- L4C9 =9= L4C1 -9- L9C1 =9=4= L9C1 -4- L8C1 =4=1= L8C1 -1- L1C1 =1= L1C9 donc L1C9 ≠ 9