Question: who was the first one to proposed the idea about atom
[{'answer': 'Leucippus', 'provenance': [{'wikipedia_id': '2844', 'title': 'Atomic theory', 'start_paragraph_id': 6, 'start_character': 227, 'end_paragraph_id': 6, 'end_character': 236, 'bleu_score': 1.0, 'section': 'Section::::History.:Philosophical atomism.\n'}]}, {'answer': 'Democritus', 'provenance': [{'wikipedia_id': '2844', 'title': 'Atomic theory', 'start_paragraph_id': 6, 'start_character': 251, 'end_paragraph_id': 6, 'end_character': 261, 'bleu_score': 1.0, 'section': 'Section::::History.:Philosophical atomism.\n'}]}]