Maestro n° 087 : Page 21 - Gr 18
L1C2 =7= L2C2 -7- L2C9 =7=1= L2C9 -1- L7C9 =1=3= L7C9 -3- L3C9 =3= L1C7 donc L1C2 ≠ 3 et L1C7 ≠ 7