Language: C++

#include <bits/stdc++.h>
using namespace std;
#define  rep(i, n) for(int i = 0; i < n; i++) 
#define  all(x) (x).begin(),(x).end()     // 昇順ソート
#define  rall(v) (v).rbegin(), (v).rend() // 降順ソート
#define  INF 1000000000
#define  pow(x) pow(10,(x)) 
typedef long long int LL;
const int MOD = 1000000007;
//sort(all(x))とするとソートできるよ

int main(){
    int n;cin >> n;
    vector<int> v(n);
    rep(i,n){
        cin >> v[i];
    }
    map<int,int> even,odd;
    rep(i,n){
        if(i % 2 == 0)odd[v[i]]++;
        else even[v[i]]++;
    }
    int even_1 = 0,even_2 =0,odd_1 = 0,odd_2 = 0;
    int e1 = 0,e2 = 0,o1 = 0,o2 = 0;

    //even mode1 roop
    int cnt = 0;
    for(auto itr = even.begin();itr != even.end();itr++){
        if(itr -> second > cnt){
            cnt = itr -> second;
            even_1 = itr -> first;
        }
    }
    e1 = cnt;
    
    cnt = 0;
    for(auto itr = even.begin();itr != even.end();itr++){
        if(itr -> second > cnt && itr -> first != even_1){
            cnt = itr -> second;
            even_2 = itr -> first;
        }
    }
    e2 = cnt;

    int cnt = 0;
    for(auto itr = odd.begin();itr < odd.end();itr++){
        if(itr -> second > cnt){
            cnt = itr -> second;
            odd_1 = itr -> first;
        }
    }
    o1 = cnt;

    cnt = 0;
    for(auto itr = odd.begin();itr < odd.end();itr++){
        if(itr -> second > ctn && itr -> first != odd_1){
            cnt = itr -> second;
            odd_2 = itr -> first;
        }
    }
    o2 = cnt;

    if(even_1 == odd_1){
        cout << min(n-e1-o2,n-e2-o1) << endl;
    }
    else{
        cout << n-e1-o1 << endl;
    }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:45:9: error: redeclaration of 'int cnt'
   45 |     int cnt = 0;
      |         ^~~
a.cc:27:9: note: 'int cnt' previously declared here
   27 |     int cnt = 0;
      |         ^~~
a.cc:46:36: error: no match for 'operator<' (operand types are 'std::_Rb_tree_iterator<std::pair<const int, int> >' and 'std::map<int, int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, int>, std::_Select1st<std::pair<const int, int> >, std::less<int>, std::allocator<std::pair<const int, int> > >::iterator'})
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                ~~~ ^ ~~~~~~~~~
      |                                |            |
      |                                |            _Rb_tree_iterator<[...]>
      |                                _Rb_tree_iterator<[...]>
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181,
                 from a.cc:1:
/usr/include/c++/14/bits/regex.h:1143:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1143 |     operator<(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1143:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
/usr/include/c++/14/bits/regex.h:1224:5: 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>&)'
 1224 |     operator<(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1224:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
/usr/include/c++/14/bits/regex.h:1317:5: 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>&)'
 1317 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1317:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
/usr/include/c++/14/bits/regex.h:1391:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1391 |     operator<(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1391:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::map<int, int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, int>, std::_Select1st<std::pair<const int, int> >, std::less<int>, std::allocator<std::pair<const int, int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
/usr/include/c++/14/bits/regex.h:1485:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1485 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1485:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
/usr/include/c++/14/bits/regex.h:1560:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1560 |     operator<(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1560:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::map<int, int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, int>, std::_Select1st<std::pair<const int, int> >, std::less<int>, std::allocator<std::pair<const int, int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
/usr/include/c++/14/bits/regex.h:1660:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1660 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1660:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
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:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'const std::pair<_T1, _T2>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'const std::reverse_iterator<_Iterator>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'const std::reverse_iterator<_Iterator>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'const std::move_iterator<_IteratorL>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'const std::move_iterator<_IteratorL>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/string_view:673:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  673 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:673:5: note:   template argument deduction/substitution failed:
a.cc:46:46: note:   'std::_Rb_tree_iterator<std::pair<const int, int> >' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   46 |     for(auto itr = odd.begin();itr < odd.end();itr++){
      |                                              ^
/usr/include/c++/14/string_view:680:5: note: candidate: 'template<c