bool won(void)
{
    int number = 1;
    for (int i = 0; i < d; i++)
    {
        if (number == d*d) return true;
        for (int j = 0; j < d; j++)
        {
            if ( board[i][j] != number )
            {
                return false;
            }
            number++;
        }
    }
    return true;
}