uses crt;
var s:string;
i:integer;
c:char;
mn, mn2 : set of char;
begin
 clrscr;
 mn:=[];
 s:='Test string.';
 for i:=1 to  length(s)-1 do
	begin
	 if s[i] in mn then mn2:=mn2+[s[i]] else
	 mn:=mn+[s[i]];
	end;
 mn:=mn-mn2;
for c:='a' to 'z' do
 if c in mn then writeln(c);
for c:='A' to 'Z' do
 if c in mn then writeln(c);

 readln
end.