documentclass{article}

usepackage[latin1]{inputenc}
usepackage{tikz}
usetikzlibrary{shapes,arrows,positioning,fit}
begin{document}
pagestyle{empty}


% Define block styles
tikzstyle{block} = [rectangle, draw, fill=yellow,
    text width=5em, text centered, rounded corners, minimum height=2em]
tikzstyle{line} = [draw, -latex']

begin{tikzpicture}[node distance = 1cm, auto]
    % Place nodes
    node [cylinder, draw, shape aspect=.5, shape border rotate=90, minimum height=1cm] (A) {A};
    node [block, below =of A] (B) {B};
    node [block, below =of B] (C) {C};
    node [block, below =of C] (D) {D};
    node [draw, fit= (C) (D)] (G) {};
    node [block, below =of D] (E) {E};
    node [text centered, below =of E] (F) {F};
    % Draw edges
    path [line] (A) -- (B);
    path [line] (B) -- (G);
    path [line] (G) -- (E);
    path [line] (E) -- (F);
end{tikzpicture}


end{document}