I know it may sound very strange at first, but Cheney was president during an astounding 4 hours and 20 minutes in 2002 and 2007 when president George W. Bush was suffering colonoscopies under sedation. This works this way due to the 25th ammendment. George H. W. Bush was also acting president during the Ronald Reagan administration but as he was elected president shortly after, there was no need to include him too