Though precipitation increases with the height, there are semiarid conditions in the nearly 7000 m towering highest mountains of the Andes. This dry steppe climate is considered to be typical of the subtropical position at 32-34° S. The valley bottoms have no woods, just dwarf scrub. The largest glaciers, as e.g. the Plomo glacier and the Horcones glaciers, do not even reach 10 km in length and have an only insignificant ice thickness. At glacial times, however, c. 20 000 years ago, the glaciers were over ten times longer. On the east side of this section of the Mendozina Andes, they flowed down to 2060 m and on the west side to c. 1220 m asl. The massifs of Cerro Aconcagua (6,961 m), Cerro Tupungato (6,550 m) and Nevado Juncal (6,110 m) are tens of kilometres away from each other and were connected by a joint ice stream network. The Andes dendritic glacier arms, i.e. components of valley glaciers, were up to 112.5 km long, over 1020, i.e. 1250 m thick and overspanned a vertical distance of 5150 altitude metres. The climatic glacier snowline (ELA) was lowered from currently 4600 m to 3200 m at glacial times.
Question: How many of the mountains are over 6500 meters tall?
Answer: 2