Language: C++

#include<bits/stdc++.h>


using namespace std;
 
int main(){
    int N,M;
    vector<string> blue(N);
    vector<string> red(N);
     map<string,int> p;
    cin >> N;
    for(int i = 0;i < N;i++){
        cin >> blue[i];
        p[blue[i]]++;
    }
    cin >> M;
    for(int i = 0;i < M;i++){
        cin >> red[i];
        p[red[i]]--;
    }

    map<string,int>::iterator post;
    int max = 0;
    
    for(post = p.begin(); p != p.end(); post++){
        if(p->second > max) max = p->second;
    }

    

    cout << max;

    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:25:29: error: no match for 'operator!=' (operand types are 'std::map<std::__cxx11::basic_string<char>, int>' and 'std::map<std::__cxx11::basic_string<char>, int>::iterator' {aka 'std::_Rb_tree<std::__cxx11::basic_string<char>, std::pair<const std::__cxx11::basic_string<char>, int>, std::_Select1st<std::pair<const std::__cxx11::basic_string<char>, int> >, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> > >::iterator'})
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                           ~ ^~ ~~~~~~~
      |                           |         |
      |                           |         std::map<std::__cxx11::basic_string<char>, int>::iterator {aka std::_Rb_tree<std::__cxx11::basic_string<char>, std::pair<const std::__cxx11::basic_string<char>, int>, std::_Select1st<std::pair<const std::__cxx11::basic_string<char>, int> >, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> > >::iterator}
      |                           std::map<std::__cxx11::basic_string<char>, int>
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: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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
/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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>' is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
/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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
/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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>::iterator' {aka 'std::_Rb_tree<std::__cxx11::basic_string<char>, std::pair<const std::__cxx11::basic_string<char>, int>, std::_Select1st<std::pair<const std::__cxx11::basic_string<char>, int> >, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
/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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
/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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>::iterator' {aka 'std::_Rb_tree<std::__cxx11::basic_string<char>, std::pair<const std::__cxx11::basic_string<char>, int>, std::_Select1st<std::pair<const std::__cxx11::basic_string<char>, int> >, std::less<std::__cxx11::basic_string<char> >, std::allocator<std::pair<const std::__cxx11::basic_string<char>, int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
/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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
/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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>' is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>' is not derived from 'const std::pair<_T1, _T2>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>' is not derived from 'const std::reverse_iterator<_Iterator>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
/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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>' is not derived from 'const std::reverse_iterator<_Iterator>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
/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:25:38: note:   'std::map<std::__cxx11::basic_string<char>, int>' is not derived from 'const std::move_iterator<_IteratorL>'
   25 |     for(post = p.begin(); p != p.end(); post++){
      |                                      ^
/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:25:38: note:   'std::map<std::__cxx11