with Ada.Text_IO, Ada.Integer_Text_IO;
use Ada.Text_IO, Ada.Integer_Text_IO;

procedure permutation is


tmp : Character;
str : String := "123";
start : Integer := 1;

procedure perms (s :  in out String; i : in Integer; n : in Integer);
procedure change (s : in out String; i : in Integer; j : in out Integer);

procedure  perms (s : in out String; i : in Integer; n : in Integer) is

j : Integer := i;

     begin
     if i = n then
         put(s);
         New_Line;
     else
        for Index in j..n loop
            change(s,i,j);
            perms(s,i+1,n);
            change(s,i,j);
        end loop;
     end if;

 end perms;


  procedure  change (s : in out String; i : in  Integer; j : in out Integer) is

  begin

    tmp  := s(i);
    s(i) := s(j);
    s(j) := tmp;
 end change;

begin
    perms(str,start,str'length);


end permutation;