30. the answer is...

the Vice President

If the president dies, resigns, or cannot work while still in office, the vice president becomes president. For this reason, the qualifications for vice president and president are the same. A vice president became president nine times in U.S. history when the president died or left office. William Henry Harrison died in office in 1841. Zachary Taylor died in office in 1850. Abraham Lincoln was killed in office in 1865. James Garfield was killed in office in 1881. William McKinley was killed in office in 1901. Warren Harding died in office in 1923. Franklin Roosevelt died in office in 1945. John F. Kennedy was killed in office in 1963. Richard Nixon resigned from office in 1974. No one other than the vice president has ever succeeded to the presidency.