Original
11 12 13 14 15
21 22 23 24 25
31 32 33 34 35
41 42 43 44 45
51 52 53 54 55

Diagonal elements are: 11 22 33 44 55 15 24 42 51

We must keep them while rotate

1x rotation
11 21 31 41 15
52 22 32 24 12
53 43 33 23 13
54 42 34 44 14
51 45 35 25 55