Maestro n° 086 : Page 84 - Gr 81
L5C7 -4- L5C4 =4= L9C4 -4-8- L9C4 =8= L3C4 -8-7- L3C4 =7= L3C8 -7- L6C8 =7= L6C7 -7-6- L6C7 =6= L5C7 donc L5C7 ≠ 4