var  s,p,k:int64;

procedure citire;
var c:char;f:text;
begin
 assign(f,'text.in');
 reset(f);
 k:=0;p:=0;s:=0;
 while not eof(f) do
  begin
   read(f,c);
   if ((ord(c)>=65)and(ord(c)<=90))or((ord(c)>=97)and(ord(c)<=122)) then begin inc(s); inc(p);end else
   if p>0 then begin inc(k); p:=0; end;
  end;
 close(f);
end;

procedure afis;
var f:text;
begin
 assign(f,'text.out');
 rewrite(f);
 writeln(f,s/k);
 close(f);
end;

begin
 citire;
 afis;
end.