Language: C++

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define INF 1e9;
using namespace std;
using ll = long long;
int count[1000000];
int main() {
    int N;
    cin >> N;
    vector <int> A(N);
    for(int i = 0; i < N; i++){
        cin >> A[i];
        count[A[i] - 1]++;
        count[A[i]]++;
        count[A[i] + 1]++;
    }
    int T = 0;
    for(int i = 0; i < 1000000; i++){
        if(count[i] > T){
            T = count[i];
        }
    }
    cout << T << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:13:9: error: reference to 'count' is ambiguous
   13 |         count[A[i] - 1]++;
      |         ^~~~~
In file included from /usr/include/c++/14/algorithm:86,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/pstl/glue_algorithm_defs.h:101:1: note: candidates are: 'template<class _ExecutionPolicy, class _ForwardIterator, class _Tp> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, typename std::iterator_traits<_II>::difference_type> std::count(_ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, const _Tp&)'
  101 | count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
      | ^~~~~
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:4025:5: note:                 'template<class _IIter, class _Tp> typename std::iterator_traits< <template-parameter-1-1> >::difference_type std::count(_IIter, _IIter, const _Tp&)'
 4025 |     count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
      |     ^~~~~
a.cc:6:5: note:                 'int count [1000000]'
    6 | int count[1000000];
      |     ^~~~~
a.cc:14:9: error: reference to 'count' is ambiguous
   14 |         count[A[i]]++;
      |         ^~~~~
/usr/include/c++/14/pstl/glue_algorithm_defs.h:101:1: note: candidates are: 'template<class _ExecutionPolicy, class _ForwardIterator, class _Tp> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, typename std::iterator_traits<_II>::difference_type> std::count(_ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, const _Tp&)'
  101 | count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
      | ^~~~~
/usr/include/c++/14/bits/stl_algo.h:4025:5: note:                 'template<class _IIter, class _Tp> typename std::iterator_traits< <template-parameter-1-1> >::difference_type std::count(_IIter, _IIter, const _Tp&)'
 4025 |     count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
      |     ^~~~~
a.cc:6:5: note:                 'int count [1000000]'
    6 | int count[1000000];
      |     ^~~~~
a.cc:15:9: error: reference to 'count' is ambiguous
   15 |         count[A[i] + 1]++;
      |         ^~~~~
/usr/include/c++/14/pstl/glue_algorithm_defs.h:101:1: note: candidates are: 'template<class _ExecutionPolicy, class _ForwardIterator, class _Tp> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, typename std::iterator_traits<_II>::difference_type> std::count(_ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, const _Tp&)'
  101 | count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
      | ^~~~~
/usr/include/c++/14/bits/stl_algo.h:4025:5: note:                 'template<class _IIter, class _Tp> typename std::iterator_traits< <template-parameter-1-1> >::difference_type std::count(_IIter, _IIter, const _Tp&)'
 4025 |     count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
      |     ^~~~~
a.cc:6:5: note:                 'int count [1000000]'
    6 | int count[1000000];
      |     ^~~~~
a.cc:19:12: error: reference to 'count' is ambiguous
   19 |         if(count[i] > T){
      |            ^~~~~
/usr/include/c++/14/pstl/glue_algorithm_defs.h:101:1: note: candidates are: 'template<class _ExecutionPolicy, class _ForwardIterator, class _Tp> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, typename std::iterator_traits<_II>::difference_type> std::count(_ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, const _Tp&)'
  101 | count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
      | ^~~~~
/usr/include/c++/14/bits/stl_algo.h:4025:5: note:                 'template<class _IIter, class _Tp> typename std::iterator_traits< <template-parameter-1-1> >::difference_type std::count(_IIter, _IIter, const _Tp&)'
 4025 |     count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
      |     ^~~~~
a.cc:6:5: note:                 'int count [1000000]'
    6 | int count[1000000];
      |     ^~~~~
a.cc:20:17: error: reference to 'count' is ambiguous
   20 |             T = count[i];
      |                 ^~~~~
/usr/include/c++/14/pstl/glue_algorithm_defs.h:101:1: note: candidates are: 'template<class _ExecutionPolicy, class _ForwardIterator, class _Tp> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, typename std::iterator_traits<_II>::difference_type> std::count(_ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, const _Tp&)'
  101 | count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
      | ^~~~~
/usr/include/c++/14/bits/stl_algo.h:4025:5: note:                 'template<class _IIter, class _Tp> typename std::iterator_traits< <template-parameter-1-1> >::difference_type std::count(_IIter, _IIter, const _Tp&)'
 4025 |     count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
      |     ^~~~~
a.cc:6:5: note:                 'int count [1000000]'
    6 | int count[1000000];
      |     ^~~~~