#!/usr/bin/env bash

INPUT_FILE=input.txt

paste \
  <(awk '{print $1}' $INPUT_FILE | sort -n ) \
  <(awk '{print $2}' $INPUT_FILE | sort -n ) |
  awk '{ $1 > $2 ? diff = ($1 - $2) : diff = ($2 - $1) ; print diff}' |
  paste -s -d "+" | 
  bc