```
class Solution(object):
def findMinArrowShots(self, points):
"""
:type points: List[List[int]]
:rtype: int
"""
points.sort(key = lambda x: x[1])
i, r = 0, 0
while i < len(points):
shoot = points[i][1]
while i < len(points) and points[i][0] <= shoot: i += 1
r += 1
return r
```