9. Please find an encryption function E: {1, 2, 3, ... 26} -＞ Z such that E(m1) + E(m2) = E(m1+m2) for every m1, m2 in {1, 2,3, ... ., 26} and please also find the decryption function corresponding to E.

(c) he first separates the programs into four of top priority, eight of lesser priority, and three of least priority, and he wishes to process the fifteen programs in such a way that the top-priority programs are processed first and the three programs of least priority are processed last?