Question 82
Given an $n \times n$ table with one of two signs "+" or "-" in any of its cells. Per move one can replace the signs in all cells of some row (or of some column) by the opposite signs. At the beginning there are exactly two minuses in the table (all other signs are pluses). After some moves the table with exactly 9 minuses is obtained.
Find the smallest and the greatest values of $n$.
(I. Voronovich)
Find the smallest and the greatest values of $n$.
(I. Voronovich)