program text_cuv;
 var
    f:text;
    s:string;
    n,i,l:byte;
    r:real
begin
 assign(f,'text.in');
 reset(f);
  read(f,s);
 close(f);
 i:=1;
  while i<=length(s) do
   begin
  while ((s[i]=' ') or (s[i]='.') or (s[i]=',')) and (i<=length(s)) do
   inc(i);
  if i<=length(s) then
   inc(n);
  while (s[i]<>' ') and (s[i]<>'.') and (s[i]<>',') and (i<=length(s)) do
   begin
    if (s[i]<>' ') and (s[i]<>'.') and (s[i]<>',') then
    inc(i);
    inc(l);
   end;
  end;
   r:=l/n
 assign(f,'text.out');
 rewrite(f);
  write(f,r);
 close(f);
end.