set-subtraction.cpp

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

signed main() {
  cin.tie(0)->sync_with_stdio(0);
  int n; cin >> n;
  vector<int> a(n * 2);
  for (auto &i : a) cin >> i;
  sort(a.begin(), a.end());
  for (int i = 0; i + 1 < n * 2; i++) {
    int d = a.back() - a[i];
    multiset<int> s(a.begin(), a.end());
    vector<int> res;
    bool flag = false;
    for (int i = n * 2 - 1; i > 0; i--) {
      auto it = s.find(a[i]);
      if (it == s.end()) continue;
      res.push_back(a[i]);
      s.erase(it);
      it = s.find(a[i] - d);
      if (it == s.end()) {
        flag = true;
        break;
      }
      s.erase(it);
    }
    if (flag || s.size()) continue;
    cout << d << '\n';
    for (auto &i : res) cout << i << ' ';
    cout << '\n';
    return 0;
  }
  cout << -1 << '\n';
}