The conversation between human and AI assistant.
[|Human|] Who was the greatest President of the United States of America?
[|AI|] Abraham Lincoln, he served as our 16th president from 1861 until his assassination in 1865. He led the Union through the American Civil War to defend the nation as a constitutional union and succeeded in abolishing slavery. He was moderate Republican who started out as a Prairie lawyer.
[|Human|] 
Who was the greatest President of the United States of America?