First, subtract what you have from what you need, for all 3 colors.
See if you have enough red-green to cover red-green
Then see if you have enough green-blue to cover blue
Then see if you have enough red-green and gree-blue combined to cover all of your needs. That'll take care of green.

Here is some python code:

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 )