uses crt;
const
 mn0=['a'..'z'];
var
 mn1:set of char;
 s: string;
 c:char;
 i:integer;
begin
 clrscr;
 writeln('Enter the string:');
 readln(s);
 mn1:=[];
 for i:=1 to length(s) do
  if (s[i] in mn0) and Not(s[i] in mn1) then mn1:=mn1+[s[i]];
 for c:='a' to 'z' do
  if c in mn1 then write(c,' ');
 readln;
end.