Language: C++

#include <bits/stdc++.h>
using namespace std;

int main() {
  int N; 
  cin >> N;
  
  string S[N];
  map<string, int> Map;
  // 文字列を読み込み，何が何回か出たか辞書を作る
  for (int i = 0; i < N; i++){
    string S;
    cin >> S;
    
    Map[S]++;
  }
  
  // 辞書を一つずつ読み込んで，最大回数を調べる．
  int MAX = 0;
  for (auto s : Map) {
    if (Map[s] > MAX) MAX = Map[s];
  }
  
  // 辞書をもう一度一つずつ読み込んで，最大回数登場した単語を拾って vec を作る
  vector<string> vec;
  for (auto s : Map) {
    if (Map[s] == MAX) vec.push_back(s);
  }
  
  // vecをsortする．
  sort(vec.begin(), vec.end());
  
  // vecを順番に出力する
  for (int i = 0; i < vec.size(); i++) {
    cout << vec.at(i) << endl;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:21:12: error: no match for 'operator[]' (operand types are 'std::map<std::__cxx11::basic_string<char>, int>' and 'std::pair<const std::__cxx11::basic_string<char>, int>')
   21 |     if (Map[s] > MAX) MAX = Map[s];
      |            ^
In file included from /usr/include/c++/14/map:63,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:152,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_map.h:504:7: note: candidate: 'std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const key_type&) [with _Key = std::__cxx11::basic_string<char>; _Tp = int; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> >; mapped_type = int; key_type = std::__cxx11::basic_string<char>]'
  504 |       operator[](const key_type& __k)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_map.h:504:34: note:   no known conversion for argument 1 from 'std::pair<const std::__cxx11::basic_string<char>, int>' to 'const std::map<std::__cxx11::basic_string<char>, int>::key_type&' {aka 'const std::__cxx11::basic_string<char>&'}
  504 |       operator[](const key_type& __k)
      |                  ~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_map.h:524:7: note: candidate: 'std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](key_type&&) [with _Key = std::__cxx11::basic_string<char>; _Tp = int; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> >; mapped_type = int; key_type = std::__cxx11::basic_string<char>]'
  524 |       operator[](key_type&& __k)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_map.h:524:29: note:   no known conversion for argument 1 from 'std::pair<const std::__cxx11::basic_string<char>, int>' to 'std::map<std::__cxx11::basic_string<char>, int>::key_type&&' {aka 'std::__cxx11::basic_string<char>&&'}
  524 |       operator[](key_type&& __k)
      |                  ~~~~~~~~~~~^~~
a.cc:21:32: error: no match for 'operator[]' (operand types are 'std::map<std::__cxx11::basic_string<char>, int>' and 'std::pair<const std::__cxx11::basic_string<char>, int>')
   21 |     if (Map[s] > MAX) MAX = Map[s];
      |                                ^
/usr/include/c++/14/bits/stl_map.h:504:7: note: candidate: 'std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const key_type&) [with _Key = std::__cxx11::basic_string<char>; _Tp = int; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> >; mapped_type = int; key_type = std::__cxx11::basic_string<char>]'
  504 |       operator[](const key_type& __k)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_map.h:504:34: note:   no known conversion for argument 1 from 'std::pair<const std::__cxx11::basic_string<char>, int>' to 'const std::map<std::__cxx11::basic_string<char>, int>::key_type&' {aka 'const std::__cxx11::basic_string<char>&'}
  504 |       operator[](const key_type& __k)
      |                  ~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_map.h:524:7: note: candidate: 'std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](key_type&&) [with _Key = std::__cxx11::basic_string<char>; _Tp = int; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> >; mapped_type = int; key_type = std::__cxx11::basic_string<char>]'
  524 |       operator[](key_type&& __k)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_map.h:524:29: note:   no known conversion for argument 1 from 'std::pair<const std::__cxx11::basic_string<char>, int>' to 'std::map<std::__cxx11::basic_string<char>, int>::key_type&&' {aka 'std::__cxx11::basic_string<char>&&'}
  524 |       operator[](key_type&& __k)
      |                  ~~~~~~~~~~~^~~
a.cc:27:12: error: no match for 'operator[]' (operand types are 'std::map<std::__cxx11::basic_string<char>, int>' and 'std::pair<const std::__cxx11::basic_string<char>, int>')
   27 |     if (Map[s] == MAX) vec.push_back(s);
      |            ^
/usr/include/c++/14/bits/stl_map.h:504:7: note: candidate: 'std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const key_type&) [with _Key = std::__cxx11::basic_string<char>; _Tp = int; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> >; mapped_type = int; key_type = std::__cxx11::basic_string<char>]'
  504 |       operator[](const key_type& __k)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_map.h:504:34: note:   no known conversion for argument 1 from 'std::pair<const std::__cxx11::basic_string<char>, int>' to 'const std::map<std::__cxx11::basic_string<char>, int>::key_type&' {aka 'const std::__cxx11::basic_string<char>&'}
  504 |       operator[](const key_type& __k)
      |                  ~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_map.h:524:7: note: candidate: 'std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](key_type&&) [with _Key = std::__cxx11::basic_string<char>; _Tp = int; _Compare = std::less<std::__cxx11::basic_string<char> >; _Alloc = std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> >; mapped_type = int; key_type = std::__cxx11::basic_string<char>]'
  524 |       operator[](key_type&& __k)
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_map.h:524:29: note:   no known conversion for argument 1 from 'std::pair<const std::__cxx11::basic_string<char>, int>' to 'std::map<std::__cxx11::basic_string<char>, int>::key_type&&' {aka 'std::__cxx11::basic_string<char>&&'}
  524 |       operator[](key_type&& __k)
      |                  ~~~~~~~~~~~^~~
a.cc:27:37: error: no matching function for call to 'std::vector<std::__cxx11::basic_string<char> >::push_back(std::pair<const std::__cxx11::basic_string<char>, int>&)'
   27 |     if (Map[s] == MAX) vec.push_back(s);
      |                        ~~~~~~~~~~~~~^~~
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53:
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = std::__cxx11::basic_string<char>; _Alloc = std::allocator<std::__cxx11::basic_string<char> >; value_type = std::__cxx11::basic_string<char>]'
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:35: note:   no known conversion for argument 1 from 'std::pair<const std::__cxx11::basic_string<char>, int>' to 'const std::vector<std::__cxx11::basic_string<char> >::value_type&' {aka 'const std::__cxx11::basic_string<char>&'}
 1283 |       push_back(const value_type& __x)
      |                 ~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = std::__cxx11::basic_string<char>; _Alloc = std::allocator<std::__cxx11::basic_string<char> >; value_type = std::__cxx11::basic_string<char>]'
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:30: note:   no known conversion for argument 1 from 'std::pair<const std::__cxx11::basic_string<char>, int>' to 'std::vector<std::__cxx11::basic_string<char> >::value_type&&' {aka 'std::__cxx11::basic_string<char>&&'}
 1300 |       push_back(value_type&& __x)
      |                 ~~~~~~~~~~~~~^~~