------
## 最终结论
```python
def big_sum(arr):
    max_value = max(arr)
    min_value = min(arr)
    return max_value + min_value

# Test cases
assert big_sum([1,2,3]) == 4
assert big_sum([-1,2,3,4]) == 3
assert big_sum([2,3,6]) == 8
```