Question: who is the ceo of what's up
[{'answer': 'Jan Koum', 'provenance': [{'wikipedia_id': '32058867', 'title': 'WhatsApp', 'start_paragraph_id': 5, 'start_character': 48, 'end_paragraph_id': 5, 'end_character': 56, 'bleu_score': 1.0, 'section': 'Section::::History.:2009–2014.\n'}]}, {'provenance': [{'wikipedia_id': '32058867', 'title': 'WhatsApp', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14414369151969868913}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '41996669', 'title': 'Brian Acton', 'section': 'Section::::Career.:Yahoo.\n', 'start_paragraph_id': 8, 'end_paragraph_id': 8, 'meta': {'evidence_span': ['In 1998, Jan Koum was hired by Yahoo as an infrastructure engineer shortly after he met Acton while working at Ernst & Young as a security tester. Over the next nine years, they worked at Yahoo. Acton invested in the dotcom boom and lost millions in the dot-com bubble of 2000. In September 2007 Koum and Acton left Yahoo and took a year off, traveling around South America and playing ultimate frisbee. Both applied, and failed, to work at Facebook. In January 2009, Koum bought an iPhone and realized that the then seven-month-old App Store was about to spawn a whole new industry of apps. He visited his friend Alex Fishman and talked about developing an app. Koum almost immediately chose the name WhatsApp because it sounded like whats up, and a week later on his birthday, Feb. 24, 2009, he incorporated WhatsApp Inc. in California. In 2014, Koum and Acton agreed to sell WhatsApp to Facebook for approximately $19 billion USD in cash and stock. Forbes estimates that Acton held over 20% stake in the company, making his net worth around $3.8 billion. According', 'In 1998, Jan Koum was hired by Yahoo as an infrastructure engineer shortly after he met Acton while working at Ernst & Young as a security tester. Over the next nine years, they worked at Yahoo. Acton invested in the dotcom boom and lost millions in the dot-com bubble of 2000. In September 2007 Koum and Acton left Yahoo and took a year off, traveling around South America and playing ultimate frisbee. Both applied, and failed, to work at Facebook. In January 2009, Koum bought an iPhone and realized that the then seven-month-old App Store was about to spawn a whole new industry of apps. He visited his friend Alex Fishman and talked about developing an app. Koum almost immediately chose the name WhatsApp because it sounded like whats up, and a week later on his birthday, Feb. 24, 2009, he incorporated WhatsApp Inc. in California. In 2014, Koum and Acton agreed to sell WhatsApp to Facebook for approximately $19 billion USD in cash and stock. Forbes estimates that Acton held over 20% stake in the company, making his net worth around $3.8 billion. According']}}]}, {'provenance': [{'wikipedia_id': '41995116', 'title': 'Jan Koum', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['Jan Koum (; born February 24, 1976) is a Ukrainian American computer programmer. He is the co-founder and was the CEO of WhatsApp, a mobile messaging application which was acquired by Facebook Inc. in February 2014 for US$19.3 billion. In 2014, he entered the Forbes list of the 400 richest Americans at position 62, with an estimated worth of more than $7.5 billion. He was the highest-ranked newcomer to the list that year. Koum was born in Kiev, Ukraine, then in the Soviet', 'Jan Koum (; born February 24, 1976) is a Ukrainian American computer programmer. He is the co-founder and was the CEO of WhatsApp, a mobile messaging application which was acquired by Facebook Inc. in February 2014 for US$19.3 billion. In 2014, he entered the Forbes list of the 400 richest Americans at position 62, with an estimated worth of more than $7.5 billion. He was the highest-ranked newcomer to the list that year. Koum was born in Kiev, Ukraine, then in the Soviet', 'Jan Koum (; born February 24, 1976) is a Ukrainian American computer programmer. He is the co-founder and was the CEO of WhatsApp,']}}]}, {'provenance': [{'wikipedia_id': '32058867', 'title': 'WhatsApp', 'section': 'Section::::History.:2009–2014.\n', 'start_paragraph_id': 5, 'end_paragraph_id': 5, 'meta': {'evidence_span': ['WhatsApp was founded in 2009 by Brian Acton and Jan Koum, former employees of Yahoo!. After leaving Yahoo! in September 2007, they took some time off in South America. At one point, they applied for jobs at Facebook but were rejected.', 'WhatsApp was founded in 2009 by Brian Acton and Jan Koum, former employees of Yahoo!. After leaving Yahoo! in September 2007, they took some time off in South America. At one point, they applied for jobs at Facebook but were rejected.']}}]}]