[ Numerical tables and their properties ] $[\quad \underline{\text { Invariants }} \quad]$

On the board, there are 10 pluses and 15 minuses. It is allowed to erase any two signs and write a plus instead if they are the same, and a minus otherwise. What sign will remain on the board after performing 24 such operations?
At each operation, the number of minuses either remains unchanged or decreases by 2. Therefore, the parity of the number of minuses does not change.

## Answer

Minus.