请根据以下文本提取所有人名和他们所在的国家。
“Barack Obama was the 44th President of the United States of America. Angela Merkel is a German politician who has been the Chancellor of Germany since 2005. Nelson Mandela was a South African anti-apartheid revolutionary and politician who served as President of South Africa from 1994 to 1999. Justin Trudeau is a Canadian politician serving as the 23rd and current Prime Minister of Canada since 2015.”
人名：Barack Obama、Angela Merkel、Nelson Mandela、Justin Trudeau
国家：美国、德国、南非、加拿大