var s, sword: set of char;
    ch: char;
begin
    s:=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'];
    sword:=[];
     repeat
         read(ch);
         case ch of
         ',','.': begin
             s:=s*sword;
             sword:=[];
         end;
       else sword:=sword+[ch];
         end;
     until ch='.';
     for ch:='a' to 'z' do
     if ch in s then write (ch:2);
     readln;
     Readln;
end.