Language: C++

#include <iostream>
#include <map>
#define ll long long
using namespace std;

void solve(){
  int n; cin >> n;
  map<int, int、greater<int>> mp;
  for(int i = 0; i < n; i++){
    int tmp; cin >> tmp;
    mp[tmp]++;
  }
  for(auto p :mp){
    if(p.second < 2) mp.erase(p); 
  }
  ll ans;
  map<int,int>::iterator itr = mp.begin();
  if(*itr.second >= 4) ans = *itr.second * *itr.second;
  else {
	int a = itr.second;
    itr++;
    int b = itr.second;
    ans = a * b;
  }
  cout << ans << endl;
}

int main(){
  solve();
  return 0; 
}

Compiler output:
a.cc:8:12: error: extended character 、 is not valid in an identifier
    8 |   map<int, int、greater<int>> mp;
      |            ^
a.cc: In function 'void solve()':
a.cc:8:12: error: 'int\U00003001greater' was not declared in this scope
    8 |   map<int, int、greater<int>> mp;
      |            ^~~~~~~~~~~~
a.cc:8:28: error: template argument 2 is invalid
    8 |   map<int, int、greater<int>> mp;
      |                            ^~
a.cc:8:28: error: template argument 4 is invalid
a.cc:11:7: error: invalid types 'int[int]' for array subscript
   11 |     mp[tmp]++;
      |       ^
a.cc:13:15: error: 'begin' was not declared in this scope; did you mean 'std::begin'?
   13 |   for(auto p :mp){
      |               ^~
      |               std::begin
In file included from /usr/include/c++/14/string:53,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/range_access.h:114:37: note: 'std::begin' declared here
  114 |   template<typename _Tp> const _Tp* begin(const valarray<_Tp>&) noexcept;
      |                                     ^~~~~
a.cc:13:15: error: 'end' was not declared in this scope; did you mean 'std::end'?
   13 |   for(auto p :mp){
      |               ^~
      |               std::end
/usr/include/c++/14/bits/range_access.h:116:37: note: 'std::end' declared here
  116 |   template<typename _Tp> const _Tp* end(const valarray<_Tp>&) noexcept;
      |                                     ^~~
a.cc:14:25: error: request for member 'erase' in 'mp', which is of non-class type 'int'
   14 |     if(p.second < 2) mp.erase(p);
      |                         ^~~~~
a.cc:17:35: error: request for member 'begin' in 'mp', which is of non-class type 'int'
   17 |   map<int,int>::iterator itr = mp.begin();
      |                                   ^~~~~
a.cc:18:11: error: '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'} has no member named 'second'
   18 |   if(*itr.second >= 4) ans = *itr.second * *itr.second;
      |           ^~~~~~
a.cc:18:35: error: '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'} has no member named 'second'
   18 |   if(*itr.second >= 4) ans = *itr.second * *itr.second;
      |                                   ^~~~~~
a.cc:18:49: error: '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'} has no member named 'second'
   18 |   if(*itr.second >= 4) ans = *itr.second * *itr.second;
      |                                                 ^~~~~~
a.cc:20:21: error: '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'} has no member named 'second'
   20 |         int a = itr.second;
      |                     ^~~~~~
a.cc:22:17: error: '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'} has no member named 'second'
   22 |     int b = itr.second;
      |                 ^~~~~~