You are given a puzzle like this:

7 __ 10 __ 2

lank may be filled with a + (plus) or - (minus), producing a value k. For all

combinations of plus and minus, find the value of k that is closest to 0.

In the above case, there are 4 combinations, each producing a different value:

7 + 10 + 2 = 19

7 + 10 - 2 = 15

7 - 10 + 2 = -1

7 - 10 - 2 = -5

Of all these combinations, the value that is closest to zero is -1

. So the answer is -1

. If

there is more than one number that is closest, print the absolute value.