var   b, i: longint;
         c: set of Char;
         a: String;  
begin
 readln(a);
 c := [];
 b := length(a);
 for i := 1 to length(a) do
  begin
   if a[i] in c
    then dec(b)
    else c := c + [a[i]];
  end;
 writeln(b);
end.
