Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| # | Name | Birth and death | Office started | Office ended |
| --- | --- | --- | --- | --- |
| 1 | Geir Vídalín | 27 October 1761\n–\n20 September 1823 | 1801 | 1823 |
| 2 | Steingrímur Jónsson |  | 1824 | 1845 |
| 3 | Helgi Thordersen | 8 April 1794\n–\n4 December 1867 | 1846 | 1866 |
| 4 | 'Pétur Pétursson | 3 October 1808\n–\n15 May 1891 | 1866 | 1889 |
| 5 | Hallgrímur Sveinsson | 5 April 1841\n–\n16 December 1909 | 1889 | 1908 |
| 6 | Þórhallur Bjarnarson | 2 December 1855\n–\n15 December 1916 | 1908 | 1916 |
| 7 | Jón Helgason | 1866\n–\n1942 | 1917 | 1939 |
| 8 | Sigurgeir Sigurðsson | 3 August 1890\n-\n13 October 1953 | 1939 | 1953 |
| 9 | Ásmundur Guðmundsson | 6 October 1888\nReykholt\n–\n29 May 1969\nReykjavík | 1954 | 1989 |
| 10 | Sigurbjörn Einarsson | 30 June 1911\nVestur-Skaftafellssýsla\n–\n28 August 2008\nReykjavík | 1959 | 1981 |
| 11 | Pétur Sigurgeirsson\n(son of Sigurgeir Sigurðsson, 8th Bishop of Iceland) | 2 June 1919\n–\n3 June 2010 | 1981 | 1989 |
| 12 | Ólafur Skúlason | 29 December 1929\n–\n9 June 2008 | 1989 | 1997 |
| 13 | Karl Sigurbjörnsson\n(son of Sigurbjörn Einarsson, 10th Bishop of Iceland) | 5 February 1947\nReykjavík | 1998 | 2012 |
| 14 | Agnes Sigurðardóttir | 19 October 1954\nÍsafjörður | 24 June 2012 | Incumbent |
Question:
who served longer, helgi thordersen or geir vidalin?
Answer:
Geir Vídalín