#!/bin/sh

day5() {
  PVAL="0"
  while read -r VAL; do
    [ $((PVAL+2 == VAL)) -eq 1 ] && PART2=$((PVAL+1))
    PVAL="$VAL"
  done
  printf "Part 1: %s\nPart 2: %s\n" "$PVAL" "$PART2"
}

tr "BFRL" "1010" | awk '{ print "ibase=2;"$1 }' | bc | uniq | sort -n | day5