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:
| City/town | Municipality | County | City/town status | Population |
| --- | --- | --- | --- | --- |
| Arendal | Arendal | Aust-Agder | 1723.0 | 39826.0 |
| Bergen | Bergen | Hordaland | 1070.0 | 263762.0 |
| Bodø | Bodø | Nordland | 1816.0 | 46049.0 |
| Drammen | Drammen | Buskerud | 1811.0 | 64597.0 |
| Egersund | Eigersund | Rogaland | 1798.0 | 13418.0 |
| Farsund | Farsund | Vest-Agder | 1795.0 | 9392.0 |
| Flekkefjord | Flekkefjord | Vest-Agder | 1842.0 | 8918.0 |
| Florø | Flora | Sogn og Fjordane | 1860.0 | 8296.0 |
| Fredrikstad | Fredrikstad | Østfold | 1567.0 | 75583.0 |
| Gjøvik | Gjøvik | Oppland | 1861.0 | 27500.0 |
| Grimstad | Grimstad | Aust-Agder | 1816.0 | 19809.0 |
| Halden | Halden | Østfold | 1665.0 | 28063.0 |
| Hamar | Hamar | Hedmark | 1248.0 | 31593.0 |
| Hammerfest | Hammerfest | Finnmark | 1789.0 | 9261.0 |
| Harstad | Harstad | Troms | 1904.0 | 23242.0 |
| Haugesund | Haugesund | Rogaland | 1854.0 | 31738.0 |
| Holmestrand | Holmestrand | Vestfold | 1752.0 | 9515.0 |
| Horten | Horten | Vestfold | 1858.0 | 24671.0 |
| Hønefoss | Ringerike | Buskerud | 1852.0 | 13930.0 |
| Kongsberg | Kongsberg | Buskerud | 1624.0 | 23997.0 |
| Kongsvinger | Kongsvinger | Hedmark | 1854.0 | 17380.0 |
| Kristiansand | Kristiansand | Vest-Agder | 1641.0 | 90562.0 |
| Kristiansund | Kristiansund | Møre og Romsdal | 1742.0 | 22661.0 |
| Larvik | Larvik | Vestfold | 1671.0 | 41221.0 |
| Lillehammer | Lillehammer | Oppland | 1842.0 | 25070.0 |
| Mandal | Mandal | Vest-Agder | 1921.0 | 13840.0 |
| Molde | Molde | Møre og Romsdal | 1742.0 | 24421.0 |
| Moss | Moss | Østfold | 1720.0 | 28800.0 |
| Namsos | Namsos | Nord-Trøndelag | 1845.0 | 12426.0 |
| Narvik | Narvik | Nordland | 1902.0 | 18512.0 |
| Notodden | Notodden | Telemark | 1913.0 | 12359.0 |
| Oslo | Oslo | Oslo | 1000.0 | 613285.0 |
| Porsgrunn | Porsgrunn | Telemark | 1842.0 | 33550.0 |
| Risør | Risør | Aust-Agder | 1630.0 | 6938.0 |
| Sandefjord | Sandefjord | Vestfold | 1845.0 | 42333.0 |
| Sandnes | Sandnes | Rogaland | 1860.0 | 63032.0 |
| Sarpsborg | Sarpsborg | Østfold | 1016.0 | 50115.0 |
| Skien | Skien | Telemark | 1000.0 | 72537.0 |
| Stavanger | Stavanger | Rogaland | 1125.0 | 127506.0 |
| Steinkjer | Steinkjer | Nord-Trøndelag | 1857.0 | 20672.0 |
| Søgne | Søgne | Vest-Agder | 1913.0 | 12509.0 |
| Tromsø | Tromsø | Troms | 1794.0 | 64782.0 |
| Trondheim | Trondheim | Sør-Trøndelag | 997.0 | 176348.0 |
| Tønsberg | Tønsberg | Vestfold | 871.0 | 38914.0 |
| Vadsø | Vadsø | Finnmark | 1833.0 | 6187.0 |
| Vardø | Vardø | Finnmark | 1789.0 | 2396.0 |
| Vennesla | Vennesla | Vest-Agder | 1964.0 | 13116.0 |
Question:
In which county is the city/town of Halden located?
Answer:
Østfold