Verified answer

===== PascalABC.NET =====

begin

 var b := MatrRandom(5, 5, -99, 99);

 b.Println(4);

 var n := b.RowCount;

 Print('Главная:');

 for var i := 0 to n - 1 do

   Print(b[i,i]);

 Writeln;

 Print('Побочная:');

 for var i := 0 to n - 1 do

   Print(b[i, n - i - 1]);

end.