Hi guys, my python code is as follows:

```
import numpy as np
class Solution(object):
def twoSum(self, numbers, target):
"""
:type numbers: List[int]
:type target: int
:rtype: List[int]
"""
lower = list(filter(lambda x: x < target/2,numbers))
upper = (target - np.array(numbers[len(lower):])).tolist()
result = list(set(upper).intersection(lower))
index1 = 1 + numbers.index(result[0])
index2 = 1 + numbers.index(target - result[0])
return [index1, index2]
```

I submitted that and it shows:

```
Runtime Error Message:
Line 12: IndexError: list index out of range
Last executed input: [-1,0], -1
```

I tested that on my PC, it is fine, can someone tell me where is the problem?