#include <vector>
#include <iostream>
#include <ranges>
#include <cstdlib>
#include <cmath>
#include <cassert>
#include <algorithm>

int main() {
  std::vector<int> left_list, right_list;
  int left, right;
  while (std::cin >> left >> right) {
    left_list.emplace_back(left);
    right_list.emplace_back(right);
  }
  std::sort(left_list.begin(), left_list.end());
  std::sort(right_list.begin(), right_list.end());
  assert(left_list.size() == right_list.size());
  int diff = 0;
  for(auto [left_elem, right_elem] : std::views::zip(left_list, right_list)) {
    diff += std::abs(left_elem - right_elem);
  }
  std::cout << diff << std::endl;
  return EXIT_SUCCESS;
}