Pupils sing and dance at the Nelson Mandela Square to mark the Nelson Mandela Day, in Johannesburg, South Africa, July 18, 2019. South Africans celebrate the 10th anniversary of the Nelson Mandela Day on Thursday. Mandela Day was officially declared by the United Nations in November 2009, four years before he died at the age of 95. (Xinhua/Chen Cheng)

People attend an event at the Nelson Mandela Square to mark the Nelson Mandela Day, in Johannesburg, South Africa, July 18, 2019. South Africans celebrate the 10th anniversary of the Nelson Mandela Day on Thursday. Mandela Day was officially declared by the United Nations in November 2009, four years before he died at the age of 95. (Xinhua/Chen Cheng)

Pupils sing and dance at the Nelson Mandela Square to mark the Nelson Mandela Day, in Johannesburg, South Africa, July 18, 2019. South Africans celebrate the 10th anniversary of the Nelson Mandela Day on Thursday. Mandela Day was officially declared by the United Nations in November 2009, four years before he died at the age of 95. (Xinhua/Chen Cheng)

Pupils sing and dance at the Nelson Mandela Square to mark the Nelson Mandela Day, in Johannesburg, South Africa, July 18, 2019. South Africans celebrate the 10th anniversary of the Nelson Mandela Day on Thursday. Mandela Day was officially declared by the United Nations in November 2009, four years before he died at the age of 95. (Xinhua/Chen Cheng)

Pupils sing and dance at the Nelson Mandela Square to mark the Nelson Mandela Day, in Johannesburg, South Africa, July 18, 2019. South Africans celebrate the 10th anniversary of the Nelson Mandela Day on Thursday. Mandela Day was officially declared by the United Nations in November 2009, four years before he died at the age of 95. (Xinhua/Chen Cheng)

The photo taken on July 18, 2019 shows a giant picture made of tens of thousands of tin cans to mark the Nelson Mandela Day, in Johannesburg, South Africa. South Africans celebrate the 10th anniversary of the Nelson Mandela Day on Thursday. Mandela Day was officially declared by the United Nations in November 2009, four years before he died at the age of 95. (Xinhua/Chen Cheng)