Language: C++

#include <bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    int t;
    vector<int> fi(100001),se(100001);
    for(int i = 0; i< n; i++){
        cin>>t;
        if(i%2==0){
            fi[t]++;
        }
        else{
            se[t]++;
        }
    }
    int fk=0,sk=0,fe,se;
    for(int i = 0; i < n; i++){
        if(fi[i] > 0){
            fk++;
            fe = i;
        }
        if(se[i] > 0){
            sk++;
            se = i
        }
    }
    if(fk==sk&&fk==1&&fe!=se){
        cout<<"0";
        return 0;
    }
    auto fm = max_element(fi.begin(),fi.end());
    auto sm = max_element(se.begin(),se.end());
    if(*fm != *sm){
        cout<<n/2 - *fm+n/2 - *sm;
        return 0;
    }
    auto bfm = *fm, bsm = *sm;
    fi.erase(fm),se.erase(sm);
    fm = max_element(fi.begin(),fi.end());
    sm = max_element(se.begin(),se.end());
    if(n/2-*fm+n/2-*bsm > n/2-*bfm+n/2-*sm)
        cout << n/2-*bfm+n/2-*sm;
    else
        cout<< n/2-*fm+n/2-*bsm;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:17:22: error: conflicting declaration 'int se'
   17 |     int fk=0,sk=0,fe,se;
      |                      ^~
a.cc:7:28: note: previous declaration as 'std::vector<int> se'
    7 |     vector<int> fi(100001),se(100001);
      |                            ^~
a.cc:25:18: error: no match for 'operator=' (operand types are 'std::vector<int>' and 'int')
   25 |             se = i
      |                  ^
In file included from /usr/include/c++/14/vector:72,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/vector.tcc:210:5: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(const std::vector<_Tp, _Alloc>&) [with _Tp = int; _Alloc = std::allocator<int>]'
  210 |     vector<_Tp, _Alloc>::
      |     ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/vector.tcc:211:42: note:   no known conversion for argument 1 from 'int' to 'const std::vector<int>&'
  211 |     operator=(const vector<_Tp, _Alloc>& __x)
      |               ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from /usr/include/c++/14/vector:66:
/usr/include/c++/14/bits/stl_vector.h:766:7: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(std::vector<_Tp, _Alloc>&&) [with _Tp = int; _Alloc = std::allocator<int>]'
  766 |       operator=(vector&& __x) noexcept(_Alloc_traits::_S_nothrow_move())
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:766:26: note:   no known conversion for argument 1 from 'int' to 'std::vector<int>&&'
  766 |       operator=(vector&& __x) noexcept(_Alloc_traits::_S_nothrow_move())
      |                 ~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:788:7: note: candidate: 'std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(std::initializer_list<_Tp>) [with _Tp = int; _Alloc = std::allocator<int>]'
  788 |       operator=(initializer_list<value_type> __l)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:788:46: note:   no known conversion for argument 1 from 'int' to 'std::initializer_list<int>'
  788 |       operator=(initializer_list<value_type> __l)
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
a.cc:28:25: error: no match for 'operator!=' (operand types are 'int' and 'std::vector<int>')
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                       ~~^~~~
      |                       |   |
      |                       int std::vector<int>
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181:
/usr/include/c++/14/bits/regex.h:1132:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1132 |     operator!=(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1132:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
/usr/include/c++/14/bits/regex.h:1212:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator!=(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1212 |     operator!=(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1212:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
/usr/include/c++/14/bits/regex.h:1305:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1305 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1305:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
/usr/include/c++/14/bits/regex.h:1379:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1379 |     operator!=(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1379:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   'std::vector<int>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
/usr/include/c++/14/bits/regex.h:1473:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1473 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1473:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
/usr/include/c++/14/bits/regex.h:1547:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1547 |     operator!=(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1547:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   'std::vector<int>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
/usr/include/c++/14/bits/regex.h:1647:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1647 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1647:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
/usr/include/c++/14/bits/regex.h:2213:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator!=(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)'
 2213 |     operator!=(const match_results<_Bi_iter, _Alloc>& __m1,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:2213:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'const std::__cxx11::match_results<_BiIter, _Alloc>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_pair.h:1052:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator!=(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1052 |     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1052:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'const std::pair<_T1, _T2>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:455:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  455 |     operator!=(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:455:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
/usr/include/c++/14/bits/stl_iterator.h:500:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  500 |     operator!=(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:500:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
/usr/include/c++/14/bits/stl_iterator.h:1686:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1686 |     operator!=(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1686:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
/usr/include/c++/14/bits/stl_iterator.h:1753:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1753 |     operator!=(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1753:5: note:   template argument deduction/substitution failed:
a.cc:28:27: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'int'
   28 |     if(fk==sk&&fk==1&&fe!=se){
      |                           ^~
In file includ