Let's identify the integers from the list you provided:
- -3 (integer) ✔️
- -1.5 (not an integer) ❌
- - (not a valid number) ❌
- 0 (integer) ✔️
- 1.5 (not an integer) ❌
- 3 (integer) ✔️
So, the checked integers are: -3, 0, and 3. The unchecked numbers -1.5, -, and 1.5 are examples of non-integers.