Which US president served the longest term?
Franklin D. Roosevelt is the US president who served the longest term. He was elected for four terms and served a total of 12 years in office from 1933 to 1945. Roosevelt died in office on 1945, during his fourth term.
Complete the following task based on the instruction and optional input provided.### Instruction:
Which US president served the longest term?

### Output:
Franklin D. Roosevelt is the US president who served the longest term. He was elected for four terms and served a total of 12 years in office from 1933 to 1945. Roosevelt died in office on 1945, during his fourth term.