Language: C++

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> ii;
typedef tuple<int, int, int> iii;

typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<ld> vd;
typedef vector<ll> vl;

typedef set<int> si;
typedef set<ii> sii;
typedef set<ld> sd;
typedef set<ll> sl;

typedef map<int, int> mii;
typedef priority_queue<int> pqi;
typedef queue<int> qi;
 
#define mp make_pair
#define pb push_back
#define f first
#define s second

mt19937 rng((int) std::chrono::steady_clock::now().time_since_epoch().count());

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  
  auto xorsum = [&](ll x) {
    ll res[] = {x, 1, x + 1, 0};
    return res[x % 4];
  };
  
  ll a, b;
  cin >> a >> b;
  cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
}

/*
USE LONG LONG!!!!

:pray: :fishy15:
:pray: :summitosity:
:pray: :prodakcin:

          .=     ,        =.
  _  _   /'/    )\,/,/(_   \ \
   `//-.|  (  ,\\)\//\)\/_  ) |
   //___\   `\\\/\\/\/\\///'  /
,-"~`-._ `"--'_   `"""`  _ \`'"~-,_
\       `-.  '_`.      .'_` \ ,-"~`/
 `.__.-'`/   (-\        /-) |-.__,'
   ||   |     \O)  /^\ (O/  | .        <-  BESSIE THE COW
   `\\  |         /   `\    /
     \\  \       /      `\ /
      `\\ `-.  /' .---.--.\
        `\\/`~(, '()      ('
         /(O) \\   _,.-.,_)    
        //  \\ `\'`      /
       / |  ||   `""""~"`
     /'  |__||
           `o
*/

Compiler output:
a.cc: In function 'int main()':
a.cc:44:21: error: no match for 'operator^' (operand types are 'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} and 'long long int')
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |   ~~~~~~~~~~~~~~~~~ ^~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |        |                        |
      |        |                        long long int
      |        std::basic_ostream<char>::__ostream_type {aka std::basic_ostream<char>}
a.cc:44:21: note: candidate: 'operator^(int, long long int)' (built-in)
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |   ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:44:21: 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:44:52: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::bitset<_Nb>'
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |                                                    ^
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:44:52: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |                                                    ^
/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:44:52: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |                                                    ^
/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:44:52: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'long long int'
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |                                                    ^
/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:44:52: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |                                                    ^
/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:44:52: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'long long int'
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |                                                    ^
/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:44:52: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::valarray<_Tp>'
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |                                                    ^
/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:44:52: note:   'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} is not derived from 'const std::valarray<_Tp>'
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |                                                    ^
/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:44:52: note:   mismatched types 'const std::valarray<_Tp>' and 'long long int'
   44 |   cout << xorsum(b) xor (a == 0 ? 0 : xorsum(a - 1));
      |                                                    ^
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_Openmode std::operator^(_Ios_Openmode, _Ios_Openmode)'
  144 |   operator^(_Ios_Openmode __a, _Ios_Openmode __b) _GLIBCXX_NOTHROW
      |   ^~~~~~~~
/usr/include/c++/14/bits/ios_base.h:144:27: note:   no known conversion for argument 1 from 'std::basic_ostream<char>::__ostream_type' {aka 'std::basic_ostream<char>'} to 'std::_Ios_Openmode'
  144 |   operator^(_Ios_Openmode __a, _Ios_Openmode __b) _GLIBCXX_NOTHROW
      |             ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/ios_base.h:191:3: note: candidate: 'constexpr std::_Ios_Iostate std::operator^(_Ios_Iostate, _Ios_Iostate)'