Program PascalGuru;
var s:string;
    litera:set of char;
    i:integer;
    j:char; 
begin
write('Vvedite vashe imya: '); readln(s);
for i:=1 to length(s) do
 if s[i] in ['A'..'Z'] then s[i]:=chr(ord(s[i])+32);
writeln;
for j:='a' to 'z' do
 if pos(j,s)=0 then write(j,', ');
readln;
end.