Language: C++

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

int main() {
  long long a, b;
  cin >> a >> b;
  
  if(a == b) cout << a << endl;
  else if(a + 1 == b){
    cout << a ^ b << endl;
  }
  else if(a % 2 == 0){
    if(b % 2 == 1){
      cout << ((b - a + 1) / 2) % 2 << endl;
    }
    else{
      cout << (((b - a + 1) / 2) % 2) ^ b << endl;
    }
  }
  else{
    if(b % 2 == 1){
      cout << ((b - a) / 2) % 2 ^ a << endl;
    }
    else{
      cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
    }
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:10:19: error: invalid operands of types 'long long int' and '<unresolved overloaded function type>' to binary 'operator<<'
   10 |     cout << a ^ b << endl;
      |                 ~~^~~~~~~
a.cc:17:43: error: invalid operands of types 'long long int' and '<unresolved overloaded function type>' to binary 'operator<<'
   17 |       cout << (((b - a + 1) / 2) % 2) ^ b << endl;
      |                                         ~~^~~~~~~
a.cc:22:37: error: invalid operands of types 'long long int' and '<unresolved overloaded function type>' to binary 'operator<<'
   22 |       cout << ((b - a) / 2) % 2 ^ a << endl;
      |                                   ~~^~~~~~~
a.cc:25:39: error: no match for 'operator^' (operand types are 'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} and 'long long int')
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~
      |            |                            |
      |            |                            long long int
      |            std::basic_ostream<char>::__ostream_type {aka std::basic_ostream<char>}
a.cc:25:39: note: candidate: 'operator^(int, long long int)' (built-in)
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
a.cc:25:39: note:   no known conversion for argument 1 from 'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} to 'int'
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:1:
/usr/include/c++/14/bitset:1577:5: note: candidate: 'template<long unsigned int _Nb> std::bitset<_Nb> std::operator^(const bitset<_Nb>&, const bitset<_Nb>&)'
 1577 |     operator^(const bitset<_Nb>& __x, const bitset<_Nb>& __y) _GLIBCXX_NOEXCEPT
      |     ^~~~~~~~
/usr/include/c++/14/bitset:1577:5: note:   template argument deduction/substitution failed:
a.cc:25:41: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::bitset<_Nb>'
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |                                         ^
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166:
/usr/include/c++/14/bits/valarray_after.h:410:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__bitwise_xor, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__bitwise_xor, typename _Dom1::value_type>::result_type> std::operator^(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  410 |     _DEFINE_EXPR_BINARY_OPERATOR(^, struct std::__bitwise_xor)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:410:5: note:   template argument deduction/substitution failed:
a.cc:25:41: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |                                         ^
/usr/include/c++/14/bits/valarray_after.h:410:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__bitwise_xor, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__bitwise_xor, typename _Dom1::value_type>::result_type> std::operator^(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  410 |     _DEFINE_EXPR_BINARY_OPERATOR(^, struct std::__bitwise_xor)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:410:5: note:   template argument deduction/substitution failed:
a.cc:25:41: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |                                         ^
/usr/include/c++/14/bits/valarray_after.h:410:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__bitwise_xor, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__bitwise_xor, typename _Dom1::value_type>::result_type> std::operator^(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  410 |     _DEFINE_EXPR_BINARY_OPERATOR(^, struct std::__bitwise_xor)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:410:5: note:   template argument deduction/substitution failed:
a.cc:25:41: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'long long int'
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |                                         ^
/usr/include/c++/14/bits/valarray_after.h:410:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__bitwise_xor, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__bitwise_xor, typename _Dom1::value_type>::result_type> std::operator^(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  410 |     _DEFINE_EXPR_BINARY_OPERATOR(^, struct std::__bitwise_xor)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:410:5: note:   template argument deduction/substitution failed:
a.cc:25:41: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |                                         ^
/usr/include/c++/14/bits/valarray_after.h:410:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__bitwise_xor, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__bitwise_xor, typename _Dom1::value_type>::result_type> std::operator^(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  410 |     _DEFINE_EXPR_BINARY_OPERATOR(^, struct std::__bitwise_xor)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:410:5: note:   template argument deduction/substitution failed:
a.cc:25:41: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'long long int'
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |                                         ^
/usr/include/c++/14/valarray:1201:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__bitwise_xor, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__bitwise_xor, _Tp>::result_type> std::operator^(const valarray<_Tp>&, const valarray<_Tp>&)'
 1201 | _DEFINE_BINARY_OPERATOR(^, __bitwise_xor)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1201:1: note:   template argument deduction/substitution failed:
a.cc:25:41: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::valarray<_Tp>'
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |                                         ^
/usr/include/c++/14/valarray:1201:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__bitwise_xor, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__bitwise_xor, _Tp>::result_type> std::operator^(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
 1201 | _DEFINE_BINARY_OPERATOR(^, __bitwise_xor)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1201:1: note:   template argument deduction/substitution failed:
a.cc:25:41: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::valarray<_Tp>'
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |                                         ^
/usr/include/c++/14/valarray:1201:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__bitwise_xor, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__bitwise_xor, _Tp>::result_type> std::operator^(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
 1201 | _DEFINE_BINARY_OPERATOR(^, __bitwise_xor)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1201:1: note:   template argument deduction/substitution failed:
a.cc:25:41: note:   mismatched types 'const std::valarray<_Tp>' and 'long long int'
   25 |       cout << (((b - a - 1) / 2) % 2) ^ a ^ b << endl;
      |                                         ^
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:41:
/usr/include/c++/14/cstddef:146:3: note: candidate: 'constexpr std::byte std::operator^(byte, byte)'
  146 |   operator^(byte __l, byte __r) noexcept
      |   ^~~~~~~~
/usr/include/c++/14/cstddef:146:18: note:   no known conversion for argument 1 from 'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} to 'std::byte'
  146 |   operator^(byte __l, byte __r) noexcept
      |             ~~~~~^~~
In file included from /usr/include/c++/14/streambuf:43,
                 from /usr/include/c++/14/bits/streambuf_iterator.h:35,
                 from /usr/include/c++/14/iterator:66,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:54:
/usr/include/c++/14/bits/ios_base.h:94:3: note: candidate: 'constexpr std::_Ios_Fmtflags std::operator^(_Ios_Fmtflags, _Ios_Fmtflags)'
   94 |   operator^(_Ios_Fmtflags __a, _Ios_Fmtflags __b) _GLIBCXX_NOTHROW
      |   ^~~~~~~~
/usr/include/c++/14/bits/ios_base.h:94:27: note:   no known conversion for argument 1 from 'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} to 'std::_Ios_Fmtflags'
   94 |   operator^(_Ios_Fmtflags __a, _Ios_Fmtflags __b) _GLIBCXX_NOTHROW
      |             ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/ios_base.h:144:3: note: candidate: 'constexpr std::_Ios_Ope