===== PASCALABC.NET =====

begin

 var n := ReadInteger('n =');

 var a := MatrRandom(n, n, -99, 99);

 a.Println;

 var s := 0;

 for var row := 0 to n - 2 do

   for var col := row + 1 to n - 1 do

     if a[row, col] mod 3 = 0 then

       s += a[row, col];

 Print(s)

end.