program cuv;
var f,g:text;
	  nrlitere,t,nrcuvinte:integer;
	  c:char;
	  s:string;
	  ma:real;
	  
	  
	 BEGIN
	 
	 assign(f,'text.in');
	 assign (g,'text.out');
	 reset(f);
	 rewrite(g);
	 nrlitere:=0;
	 t:=0;
	 read(f,c);
	 while (not eof ) do begin
		if ((c>='a') and (c<'z')) or ((c>='A') and (c<='Z')) then begin
			nrlitere:=nrlitere+1;
			if t=0 then nrcuvinte:=nrcuvinte+1;
			t:=1; end
		else
			t:=0;
		read(f,c);
                end;
ma:=nrlitere/nrcuvinte;
write(g,ma);
close(f);
close(g);
end.