4. (7 points) Provide an example of an expression consisting of ones, parentheses, and the signs «+» and «X», such that

- its value is 11
- if in this expression all signs «+» are replaced with signs «X», and signs «X» with signs «+», the result is still 11.
Solution. Here is one of the possible examples:

$$
1+1+1+1+1+1+1+1+1+1+1 \times 1 \times 1 \times 1 \times 1 \times 1 \times 1 \times 1 \times 1 \times 1 \times 1
$$

Criteria. Any correct example: 7 points.

Conceptually correct example, not working due to a technical error (something like an extra or missing one in the example above): 2 points. Any incorrect example: 0 points.