Y by
Numbers
are written on a board.
and
plays the following game: They take turns choosing a number from the board and deleting them.
starts first. They sum all the deleted numbers. If after a player's turn (after he deletes a number on the board) the sum of the deleted numbers can't be expressed as difference of two perfect squares,then he loses, if not, then the game continues as usual. Which player got a winning strategy?



