digraph G {
N1 -> N5
N1 -> N6
N2 -> N1
N3 -> N2
N4 -> N2
N7 -> N3
N7 -> N4
N1 [ label="+",  shape="parallelogram"]
N2 [ label="[",  shape="parallelogram"]
N3 [ label="min",  shape="ellipse"]
N4 [ label="max",  shape="ellipse"]
N5 [ label="a",  shape="box"]
N6 [ label="42",  shape="box"]
N7 [ label="/",  shape="parallelogram"]

}