IN THE GRID BELOW, EACH LETTER REPRESENTS A DIFFERENT INTEGER FRO...

20. In the grid below, each letter represents a different integer from 1 to 7. When

comparing the sum of the numbers in any row or column to that of any other

rows or columns, the two sums must be of the same parity (either both even or

both odd) and differ by at most 2. Find the sum of all possible values of a.

a b

c d e

f g