Question: what is the coast guard emergency hf frequency
[{'answer': 'digital 406 MHz signals', 'provenance': [{'wikipedia_id': '14912872', 'title': 'International distress frequency', 'start_paragraph_id': 5, 'start_character': 234, 'end_paragraph_id': 5, 'end_character': 257, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '14912872', 'title': 'International distress frequency', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 395, 'bleu_score': 0.9405915740399611, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5434866324879961727}, 'section': 'Section::::History.\n'}]}]