Who would have been the President had someone assasinated Abraham Lincoln before he took the oath of office the first time?

What does the oath of office mean?  Why was Abraham Lincoln assasinated?  Why did abraham lincoln left office?  When did president Lincoln take office?  Who succeded abraham lincoln in office?  Who performs the presidential oath of office?  Who was president after lincoln was assasinated?  Who became president after lincoln was assasinated?  Which US President were assasinated while in office?  Who took over as president after lincoln was assasinated?  Who became President when Abraham Lincoln died in office?  What oath is taken by the president before taking office?  3rd president to be assasinated and 5th to die in office?  Who became president after abraham lincoln died in office?  How did abraham lincoln leave the office of the president?  Does Abraham Lincoln have any regrets about his term in office?  Was abraham lincoln alive at the same time as benjamin franklin?  Which of these men became president when abraham lincoln died in office?  Was Abraham Lincoln president by the time he was in the American Revolution?