S =REVERSE(INPUT)
L D =&UCASE &LCASE
M EQ(ORD(S),ORD(D)) (O =O CHAR(ORD(S)))
 D =LNE(D,'z') SUBSTR(D,2) :S(M)
 S =NE(SIZE(S),1) SUBSTR(S,2) :S(L)
 OUTPUT =O
END