The following game is played on a rectangular chessboard of size 5*7 (i.e. there are 5 rows of squares each row containing 7 squares). Initially a number of coins are randomly placed on some of the squares, no square containing more than one coin. A complete move consists of moving every coin from the square containing it to another square subject to the following rules
i. every coin may be moved one square up or down, or left or right of the square it occupies to an adjacent square;
ii. if a particular coin is moved up or down as part of a complete move, then it must be moved left or right in the next complete move;
iii. if a particular coin is moved left or right as part of a complete move, then it must be moved up or down in the next complete move;
iv. at the end of each complete move, no square can contain two or more coins.

The game stops if it becomes impossible to make a complete move.

I. Show that if initially 25 coins are placed on the board, then the game must eventually stop.

II. Show that it is possible to place 24 coins on the board in such a way that the game could go on forever.