Who was president in 1945 of brainboost?

In 1945, the President of the United States was Harry S. Truman. He assumed office on April 12, 1945, following the death of Franklin D. Roosevelt. Truman led the country through the final stages of World War II and the beginning of the Cold War. If you're referring to a different "BrainBoost," please provide more context for an accurate response.