Maestro n° 103 : Page 57 - Gr 54
r5c6 =6= r7c6 -6- r7c8 =6=8= r7c8 -8- r8c9 =8= r8c3 -8- r6c3 =8= r6c2 -8-4- r6c2 =4= r6c5 => r5c6 ≠ 4 and r6c5 ≠ 6