给定一组字符串，请使用Python代码找出其中最长和最短的字符串，并输出它们。


["apple", "banana", "orange", "grape", "watermelon"]
```python
strings = ["apple", "banana", "orange", "grape", "watermelon"]
min_string = min(strings, key=len)
max_string = max(strings, key=len)
print("Min string: ", min_string)
print("Max string: ", max_string)
```