Language: C++

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

/* #pragma */
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")


/*alias*/
#define F first
#define S second

#define y0 y3487465
#define y1 y8687969
#define j0 j1347829
#define j1 j234892
#define next asdnext
#define prev asdprev
#define itn int

/*template*/
template<class T>inline bool amax(T &a, const T &b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>inline bool amin(T &a, const T &b) { if (b < a) { a = b; return 1; } return 0; }

/* func */
int32_t GCD(int32_t a, int32_t b){return b ? GCD(b, a%b) : a;}
int64_t GCD(int64_t a, int64_t b){return b ? GCD(b, a%b) : a;}
int32_t LCM(int32_t a, int32_t b){return a * b / GCD(a, b);}
int64_t LCM(int64_t a, int64_t b){return a * b / GCD(a, b);}

/*struct*/
struct aaa {
	aaa() {
		cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20);
	};
}aaaaaaa;

/* const */
constexpr int32_t INF = 1001001001;
constexpr int64_t LINF = 1001001001001001001ll;
constexpr int32_t MOD = 1e9 + 7; //10^9
constexpr int64_t EPS = 1e-9;
constexpr int32_t dx[] = { 1, 1, 0, -1, -1, -1, 0, 1 }, dy[] = { 0, 1, 1, 1, 0, -1, -1, -1 };
//constexpr int32_t dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
//Counterclockwise from the 6o'clock direction
//Take the x-axis downward and the y-axis right


//g++ -std=c++14 -Wall --pedantic-errors -o template template.cpp
//g++ -std=c++14 -Wall --pedantic-errors template.cpp
//chcp 65001

/*global*/



//#define int int64_t
signed main()
{
	int n; cin >> n;
	vector<int> a(n+1);
	for(int i = 0, i_len = (int)n+1; i < i_len; ++i) cin >> a[i+1];
	vector<int> b(n+1);

	for(int i = n; i >= 1; --i)
	{
		int sum{};
		for(int j = i+i; j <= n; j += i)
		{
			sum ^= b[j];
		}
		b[i] = sum^s[i];
	}	
	vector<int> ans;
	for(int i = 1; i <= n; ++i)
	{
		if(b[i]) ans.emplace_back(i);
	}
	cout << ans.size() << '\n';
	for(int i = 0; i < ans.size(); ++i)
	{
		cout << ans[i] << i+1==ans.size()?'\n':' ';
	}
}

Compiler output:
a.cc: In function 'int main()':
a.cc:72:28: error: 's' was not declared in this scope
   72 |                 b[i] = sum^s[i];
      |                            ^
a.cc:82:38: error: no match for 'operator==' (operand types are 'std::basic_ostream<char>' and 'std::vector<int>::size_type' {aka 'long unsigned int'})
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                 ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
      |                                |               |
      |                                |               std::vector<int>::size_type {aka long unsigned int}
      |                                std::basic_ostream<char>
a.cc:82:38: note: candidate: 'operator==(int, std::vector<int>::size_type {aka long unsigned int})' (built-in)
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                 ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
a.cc:82:38: note:   no known conversion for argument 1 from 'std::basic_ostream<char>' to '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: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:82:49: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
/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:82:49: note:   'std::basic_ostream<char>' is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
/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:82:49: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
/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:82:49: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'std::vector<int>::size_type' {aka 'long unsigned int'}
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
/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:82:49: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
/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:82:49: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'std::vector<int>::size_type' {aka 'long unsigned int'}
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
/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:82:49: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
/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:82:49: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
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:82:49: note:   'std::basic_ostream<char>' is not derived from 'const std::pair<_T1, _T2>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
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:82:49: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
/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:82:49: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
/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:82:49: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
/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:82:49: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   82 |                 cout << ans[i] << i+1==ans.size()?'\n':' ';
      |                                                 ^
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/substitu