Language: C++

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,n) for(int i=0; (i)<(n); ++(i))
#define rep1(i,n) for(int i=1; (i)<(n); ++(i))
#define maxi(v) distance(v.begin(), max_element(v.begin(), v.end()))
#define mini(v) distance(v.begin(), min_element(v.begin(), v.end()))
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
const long long llINF = 1LL<<60;
const int INF = 1e9;

int main(){
    int n; cin >> n;
    vector<int> v(n); rep(i,n) cin >> v[i];
    //int k=0;
    sort(v,begin, v.end());
    if(n%2==0) cout << v[n/2+1]-v[n/2];
    else cout << 0;

    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:17:9: error: no matching function for call to 'sort(std::vector<int>&, <unresolved overloaded function type>, std::vector<int>::iterator)'
   17 |     sort(v,begin, v.end());
      |     ~~~~^~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/algorithm:61,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algo.h:4762:5: note: candidate: 'template<class _RAIter> void std::sort(_RAIter, _RAIter)'
 4762 |     sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
      |     ^~~~
/usr/include/c++/14/bits/stl_algo.h:4762:5: note:   candidate expects 2 arguments, 3 provided
/usr/include/c++/14/bits/stl_algo.h:4793:5: note: candidate: 'void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = vector<int>; _Compare = __gnu_cxx::__normal_iterator<int*, vector<int> >]'
 4793 |     sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
      |     ^~~~
/usr/include/c++/14/bits/stl_algo.h:4793:63: note:   no known conversion for argument 2 from '<unresolved overloaded function type>' to 'std::vector<int>'
 4793 |     sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
      |                                         ~~~~~~~~~~~~~~~~~~~~~~^~~~~~
In file included from /usr/include/c++/14/algorithm:86:
/usr/include/c++/14/pstl/glue_algorithm_defs.h:292:1: note: candidate: 'template<class _ExecutionPolicy, class _RandomAccessIterator, class _Compare> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void> std::sort(_ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator, _Compare)'
  292 | sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp);
      | ^~~~
/usr/include/c++/14/pstl/glue_algorithm_defs.h:292:1: note:   candidate expects 4 arguments, 3 provided
/usr/include/c++/14/pstl/glue_algorithm_defs.h:296:1: note: candidate: 'template<class _ExecutionPolicy, class _RandomAccessIterator> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void> std::sort(_ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator)'
  296 | sort(_ExecutionPolicy&& __exec, _RandomAccessIterator __first, _RandomAccessIterator __last);
      | ^~~~
/usr/include/c++/14/pstl/glue_algorithm_defs.h:296:1: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/14/pstl/glue_algorithm_defs.h:15:
/usr/include/c++/14/pstl/execution_defs.h: In substitution of 'template<class _ExecPolicy, class _Tp> using __pstl::__internal::__enable_if_execution_policy = typename std::enable_if<__pstl::execution::v1::is_execution_policy<typename std::remove_cv<typename std::remove_reference<_Tp>::type>::type>::value, _Tp>::type [with _ExecPolicy = std::vector<int>&; _Tp = void]':
/usr/include/c++/14/pstl/glue_algorithm_defs.h:296:1:   required by substitution of 'template<class _ExecutionPolicy, class _RandomAccessIterator> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, void> std::sort(_ExecutionPolicy&&, _RandomAccessIterator, _RandomAccessIterator) [with _ExecutionPolicy = std::vector<int>&; _RandomAccessIterator = __gnu_cxx::__normal_iterator<int*, std::vector<int> >]'
a.cc:17:9:   required from here
   17 |     sort(v,begin, v.end());
      |     ~~~~^~~~~~~~~~~~~~~~~~
/usr/include/c++/14/pstl/execution_defs.h:82:7: error: no type named 'type' in 'struct std::enable_if<false, void>'
   82 | using __enable_if_execution_policy =
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~