<kmc> addquote <LKoen> kmc: it\'s 3am and instead of going to bed I just spent a looot of time reading a long article about circadian rythms and melatonin

#!/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