MathDB

8

8

board (with

64

1

1

squares) is painted white. We are allowed to choose any rectangle consisting of

3

of the

64

squares and paint each of the

3

squares in the opposite colour (the white ones black, the black ones white). Is it possible to paint the entire board black by means of such operations?
(IS Rubanov, Kirov)

(269) 3

Problems(1)