need_red, need_green, need_blue = [int(x.strip()) for x in input().strip().split()]
red, green, blue = [int(x.strip()) for x in input().strip().split()]
red_green,  green_blue = [int(x.strip()) for x in input().strip().split()]

need_red = max( need_red-red, 0 )
need_green = max( need_green-green, 0 )
need_blue = max( need_blue-blue, 0 )

print( need_red+need_green+need_blue\
    if need_red<=red_green\
    and need_blue<=green_blue\
    and need_red+need_green+need_blue<=red_green+green_blue\
    else -1 )