Table:
text: List of highest points of Norwegian counties
Highest points by former counties
Highest points by former counties
Rank_ County Name_ Type_ Elevation
16 Akershus Fjellsjøkampen mountain m (ft)
17 Vestfold Skibergfjellet mountain m (ft)
18 Oslo Kjerkeberget hill m (ft)
19 Østfold Slavasshøgda hill m (ft)

Question: From the list of the highest points in Norwegian counties, tell me the altitude for Oslo. ?