Language: C++

#include <bits/stdc++.h>
#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define ll long long
#define INF 999999999
using namespace std;
int main() {
  ll N;
  ll count = 0;
  std::vector<ll> A(N+1);
  std::vector<ll> B(N+1);
  std::map<ll, ll> M;
  for (ll i = 1; i < N+1; i++) {
    ll a;
    std::cin >> a;
    A[i] = a+i;
    if (M[a-i] == M.end() ) {
        M[a-i] = 0;
} else {
        M[a-i] = M[a-i]+1;
}
  }
  for (ll i = 1; i < A.size()+1; i++) {
    count +=M[A[i]];
  }
  std::cout << (count-N)/2 << '\n';
}


Compiler output:
a.cc: In function 'int main()':
a.cc:18:16: error: no match for 'operator==' (operand types are 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'} and 'std::map<long long int, long long int>::iterator' {aka 'std::_Rb_tree<long long int, std::pair<const long long int, long long int>, std::_Select1st<std::pair<const long long int, long long int> >, std::less<long long int>, std::allocator<std::pair<const long long int, long long int> > >::iterator'})
   18 |     if (M[a-i] == M.end() ) {
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:1103:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1103 |     operator==(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1103:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
/usr/include/c++/14/bits/regex.h:1199:5: 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>&)'
 1199 |     operator==(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1199:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
/usr/include/c++/14/bits/regex.h:1274:5: 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>&)'
 1274 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1274:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
/usr/include/c++/14/bits/regex.h:1366:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1366 |     operator==(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1366:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   'std::map<long long int, long long int>::iterator' {aka 'std::_Rb_tree<long long int, std::pair<const long long int, long long int>, std::_Select1st<std::pair<const long long int, long long int> >, std::less<long long int>, std::allocator<std::pair<const long long int, long long int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
/usr/include/c++/14/bits/regex.h:1441:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1441 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1441:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
/usr/include/c++/14/bits/regex.h:1534:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1534 |     operator==(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1534:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   'std::map<long long int, long long int>::iterator' {aka 'std::_Rb_tree<long long int, std::pair<const long long int, long long int>, std::_Select1st<std::pair<const long long int, long long int> >, std::less<long long int>, std::allocator<std::pair<const long long int, long long int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
/usr/include/c++/14/bits/regex.h:1613:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1613 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1613:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
/usr/include/c++/14/bits/regex.h:2186:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator==(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)'
 2186 |     operator==(const match_results<_Bi_iter, _Alloc>& __m1,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:2186:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::__cxx11::match_results<_BiIter, _Alloc>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
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:1033:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1033 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1033:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::pair<_T1, _T2>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:441:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  441 |     operator==(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:441:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
/usr/include/c++/14/bits/stl_iterator.h:486:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  486 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1667 |     operator==(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1737 |     operator==(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long int'}
   18 |     if (M[a-i] == M.end() ) {
      |                         ^
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:192:5: note: candidate: 'template<class _StateT> bool std::operator==(const fpos<_StateT>&, const fpos<_StateT>&)'
  192 |     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:192:5: note:   template argument deduction/substitution failed:
a.cc:18:25: note:   mismatched types 'const std::fpos<_StateT>' and 'std::map<long long int, long long int>::mapped_type' {aka 'long long