To define a set of elements, put the elements separated by a comma, with
%{ ... %} or set[ ... ] as delimiters.

Input :

%{1,2,3,4%}

set[1,2,3,4]

set[1,2,3,4]

In the Xcas answers, the set delimiters are displayed
as and in order
not to confuse sets with lists.
For example, 1,2,3 is the set %{1,2,3%},
unlike [1,2,3] (normal brackets) which is the list [1,2,3].

Input :

A:=%{1,2,3,4%} or A:=set[1,2,3,4]

Output :

1,2,3,4

Input :

B:=%{5,5,6,3,4%} or B:=set[5,5,6,3,4]

Output :

5,6,3,4

Remark

The order in a set is not significant and
the elements in a set are all distinct. If you input
B:=%{5,5,6,3,4%} and C:=%{3,4,5,3,6%}, then
B==C will return 1.