var f,g:text;
    nr,i,k:longint;
    s:string;
begin
assign(f,'text.in'); reset(f);
assign(g,'text.out'); rewrite(g);
readln(f,s);
s:=s+'  ';
i:=1;
while i<length(s) do begin
 if ((ord(s[i])>=ord('A')) and (ord(s[i])<=ord('z'))) then begin
                                                        inc(k);
                                                        inc(i);
                                                        end
              else begin
               inc(nr);
               while (ord(s[i])<ord('A')) or (ord(s[i])>ord('z')) and (i<length(s))  do inc(i);
               end;
          end;
if trunc(k/nr)=k/nr then write(g,trunc(k/nr))
                    else write(g,k/nr:4:2);
close(f);
close(g);
end.