Maestro n° 101 : Page 82 - Gr 79
L7C5 -6- L7C3 =6= L8C3 -6-3- L8C3 =3= L8C7 -3- L9C7 =3=5= L9C7 -5- L9C5 =5= L7C5 donc L7C5 ≠ 6