What river flows through both Austria and Romania?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'QUESTIONS_ENTITY', 'name_': 'Q40', 'id': 0, 'label': 'Austria'}, {'type': 'QUESTIONS_ENTITY', 'name_': 'Q218', 'id': 1, 'label': 'Romania'}, {'type': 'INTERNAL', 'name_': 'Q9067', 'id': 2, 'label': 'Hungarian'}, {'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q179779', 'id': 3, 'label': 'Bacău County'}], 'links': [{'name_': 'P17', 'source': 2, 'target': 0, 'label': 'country'}, {'name_': 'P17', 'source': 2, 'target': 1, 'label': 'country'}, {'name_': 'P2341', 'source': 2, 'target': 3, 'label': 'indigenous to'}, {'name_': 'P17', 'source': 3, 'target': 1, 'label': 'country'}]}