Question: which contingent leads the march past in all the olympic games
[{'answer': 'Greece', 'provenance': [{'wikipedia_id': '19920508', 'title': 'Olympic Games ceremony', 'start_paragraph_id': 1, 'start_character': 333, 'end_paragraph_id': 1, 'end_character': 339, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '19920508', 'title': 'Olympic Games ceremony', 'start_paragraph_id': 14, 'start_character': 0, 'end_paragraph_id': 14, 'end_character': 677, 'bleu_score': 0.9303262325121341, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 28039982915446752}, 'section': 'Section::::Opening.:Parade of Nations.\n'}]}]