var f,g:text;
    x:char;
    nr,s:longint;
begin
assign(f,'text.in');reset(f);
assign(g,'text.out');rewrite(g);
nr:=0;s:=0;
while not eof(f) do
      begin
      read(f,x);
      if x in['a'..'z','A'..'Z'] then begin
                                      inc(nr);
                                      while not eof(f)and(x in ['a'..'z','A'..'Z'])do
                                            begin
                                            inc(s);
                                            read(f,x);
                                            end;
                                      end;
      end;
writeln(g,s div nr);
close(f);
close(g);
end.