Odd

From BluWiki

The board must be completely filled, and the sum of the number of distinct red connected groups and the number of distinct blue connected groups must be odd. Typically, one only counts connected groups that are above a certain minimum size in order to determine the winner. Therefore, the player who proposes this pattern must also specify this minimum size. The figure shows an example of the successfully-completed pattern for a minimum size of 7. There are 5 groups which each consist of 7 or more cells. Although the board is full in the example, in actual play it will become obvious who the winner will be well before the board is full, so most games will end with a resignation.