Danila the Magician and Mia the Assistant are showing a trick with a board.
First, Danila secludes himself, while Mia asks the audience to fill the 8×8 square table drawn on the board: each cell can contain either zero or one.
Next, another member of the audience chooses the secret number: an integer from 1 to 64. The number is announced to Mia but not to Danila.
After that, Mia comes to the board and changes exactly one number on it: either a zero into one, or a one into zero.
Finally, Danila returns, looks at the board for a while, and happily announces the secret number he did not know.
How do they perform the trick? Help Danila and Mia to prepare and then show it.