func_code_string: #include <bits/stdc++.h>   using namespace std;   const double pi = acos(-1.0);   const int N = 1e5;   int main() {     ios::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     int tc, ca = 0;     cin >> tc;     while (tc--) {       int n, el;       vector<int> v;       cin >> n;       for (int i = 0; i < n + n; i++) {         cin >> el;         v.push_back(el);       }       sort(v.begin(), v.end());       cout << v[n] - v[n - 1] <<   n ;     }     return 0;   }   