>>> import networkx as nx

>>> g=nx.DiGraph()
>>> k = g.add_edge('Barcelona', 'Igualada')
>>> k = g.add_edge('Igualada', 'Cervera')
>>> k = g.add_edge('Cervera', 'Tarrega')


>>> import ex2

>>> ex2.parades(g, 'Barcelona', 'Cervera')
(1, ['Igualada'])
>>> ex2.parades(g, 'Barcelona', 'Tarrega')
(2, ['Igualada', 'Cervera'])
>>> ex2.parades(g, 'Barcelona', 'Cerveraaa')
(-1, [])


----

>>> g = nx.DiGraph()
>>> g.add_path([1, 2, 3, 4])
>>> g.add_path([1, 2, 5, 6, 4])

>>> ex2.parades(g, 1, 4)
(2, [2, 3])
>>> ex2.parades(g, 2, 6)
(1, [5])
>>> ex2.parades(g, 4, 6)
(-1, [])