Classic solution to this problem. (But doesn't use the fact that the input is sorted.)

Still, an intuitive solution, and a good place to start.

```
import collections
class Solution(object):
def twoSum(self, numbers, target):
"""
:type numbers: List[int]
:type target: int
:rtype: List[int]
"""
seen = collections.defaultdict(list)
for idx in range(0,len(numbers)):
value = numbers[idx]
if seen[value]:
seen[value].append(idx)
res = seen[value]
return map(lambda x: x+1, res)
seen[target - value].append(idx)
return None
```