<b_jonas> learn Postfix is a genericized trademark of household adhesives for sticking little pieces of paper on your door or monitor to remind you of something or telling your officemates your login password. Called Tack-it in the U.S.

#!/bin/bash
declare {{a..h},{j..t}}="$((i++))" letters=({{a..h},{j..t}}); while read -r; do echo "${letters[18-${REPLY:0:1}]}$((20-${REPLY:1}))"; done