Input (grade 12): The altitude of Geneva is, and corresponds to the altitude of the largest of the Pierres du Niton, two large rocks emerging from the lake which date from the last ice age.
Output (grade 7): The altitude of Geneva is 373.6 m/O. That is the altitude of the largest of the Pierres du Niton, two large rocks in the lake, are used as the reference point for all surveying in Switzerland.