#{ lib }:
let
  lib = import<nixpkgs/lib>;
  filePath = ./example.txt; # Path to the file
  fileContent = builtins.readFile filePath;
  lines = lib.strings.splitString "\n" fileContent;
  filterNonEmpty = word: word != "";
  isEmptyPair = pair: (pair[0] == null || pair[0] == "") && (pair[1] == null || pair[1] == "");
  processWord = word: lib.strings.toInt word;
  processLine = line: map processWord (lib.lists.filter filterNonEmpty (lib.strings.splitString " " line));
  calculateDistance = pairs:
    let 
      x = builtins.elemAt pairs 0;
      y = builtins.elemAt pairs 1;
    in
      y - x;
  processedLines = lib.lists.filter (list: (builtins.length list) > 0) (map processLine lines);
  distances = map calculateDistance processedLines;
  sum = lib.lists.fold (a: b: a + b) 0 distances;
in
  sum