Maestro n° 103 : Page 86 - Gr 83
r3c1 =4= r3c4 -4- r8c4 =4=7= r8c4 -7- r8c9 =7=1= r8c9 -1- r9c8 =1= r2c8 -1-9- r2c8 =9= r1c8 -9-5- r1c8 =5= r7c8 -5- r8c7 =5= r8c1 => r8c1 ≠ 4 and r3c1 ≠ 5