Language: C++

#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define SP << " " 
#define LLi long long int

using namespace std;

int imax=2147483647;
long long int llimax=9223372036854775807;

struct kaz{
	int val;
	int num;

	bool operator<(const kaz &in) const{
		return val!=in.val ? val>in.val : num<in.num;
	};
};

int main(){

	int h, w, m, ih, iw, tmp, che, ma=0;
	vector<int> a, b;
	vector<kaz> aa, bb;
	map<kaz, int> mp;
	kaz tmpk;

	cin>> h >> w >> m;
	a.resize(h);
	b.resize(w);
	aa.resize(h);
	bb.resize(w);

	rep(i, m){
		cin >> ih >> iw;
		ih--;
		iw--;
		tmpk.val=ih;
		tmpk.num=iw;
		mp[tmpk]=i+1;
		a[ih]++;
		b[iw]++;
	}

	rep(i, h) {
		aa[i].val=a[i];
		//cout<< a[i] << " " << b[i] <<endl;
		aa[i].num=i;
	}
	rep(i, w) {
		bb[i].val=b[i];
		//cout<< a[i] << " " << b[i] <<endl;
		bb[i].num=i;
	}
	
	sort(aa.begin(), aa.end());
	sort(bb.begin(), bb.end());

	/*for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			tmpk.val=i;
			tmpk.num=j;
			cout<< mp[tmpk] <<endl;
		}
	}*/

	//cout<< mp.size() <<endl;

	int flag=0;

	for(int i=0;i<h;i++){
		if(i>0 && aa[i-1]!=aa[i]) break;
		for(int j=0;j<w;j++){
			if(flag) break;
			if(j>0 && bb[j-1]!=bb[j]) flag=1;
			tmp=aa[i].val+bb[j].val;
			tmpk.val=aa[i].num;
			tmpk.num=bb[j].num;
			if(mp.count(tmpk)){
				tmp--;
				//cout<< i << j <<endl;
			}
			ma=max(ma, tmp);
		}
	}

	cout<< ma <<endl;
 
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:74:34: error: no match for 'operator!=' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} and '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'})
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
/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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
/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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
/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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
/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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
/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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
/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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
/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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::pair<_T1, _T2>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::reverse_iterator<_Iterator>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
/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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::reverse_iterator<_Iterator>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
/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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::move_iterator<_IteratorL>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
/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:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::move_iterator<_IteratorL>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
In file included from /usr/include/c++/14/bits/char_traits.h:42,
                 from /usr/include/c++/14/string:42,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/postypes.h:197:5: note: candidate: 'template<class _StateT> bool std::operator!=(const fpos<_StateT>&, const fpos<_StateT>&)'
  197 |     operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:197:5: note:   template argument deduction/substitution failed:
a.cc:74:40: note:   '__gnu_cxx::__alloc_traits<std::allocator<kaz>, kaz>::value_type' {aka 'kaz'} is not derived from 'const std::fpos<_StateT>'
   74 |                 if(i>0 && aa[i-1]!=aa[i]) break;
      |                                        ^
In file included from /usr/include/c++/14/string:43:
/usr/include/c++/14/bits/allo