Language: C++

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

#define trace(...) __f( #__VA_ARGS__ , __VA_ARGS__ )
template <typename Arg1>
void __f( const char* name , Arg1&& arg1 ) {
        cerr << name << " : " << arg1 << "\n";
}
template <typename Arg1, typename... Args>
void __f( const char* na , Arg1&& arg1 , Args&&... args ) {
        const char* c = strchr( na + 1 , ',' );
        cerr.write( na , c - na ) << " : " << arg1 << " , ";
        __f( c + 1 , args... );
}
#define endl "\n"
#define all(V) V.begin(),V.end()
#define Unique(V) sort(all(V)),V.erase(unique(all(V)),V.end())
#define IO ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
typedef long long int LL;
typedef pair <int,int> pii;
const int MOD = 1e9 + 7;
const int inf = 1e9;
const double EPS = 1e-9;
const double PI = acos(-1.0);
const long long INF = 1e18;
const int N = 1e5 + 5;

int main( ) {
        IO;
        #ifdef LOCAL
            freopen( "input.txt" , "r" , stdin );
        #endif // LOCAL
        int a , b;
        cin >> a >> b;
        if( a >= 13 ) return cout << a + b < endl,0;
        if( a >= 6 && a <= 12 ) return cout << a + b/2 << endl,0;
        cout << 0 << endl;
        return 0;
}










Compiler output:
a.cc: In function 'int main()':
a.cc:35:44: error: no match for 'operator<' (operand types are 'std::basic_ostream<char>' and 'const char [2]')
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                              ~~~~~~~~~~~~~ ^
      |                                   |
      |                                   std::basic_ostream<char>
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:1143:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1143 |     operator<(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1143:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
/usr/include/c++/14/bits/regex.h:1224:5: 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>&)'
 1224 |     operator<(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1224:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
/usr/include/c++/14/bits/regex.h:1317:5: 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>&)'
 1317 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1317:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
/usr/include/c++/14/bits/regex.h:1391:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1391 |     operator<(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1391:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'const char [2]'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
/usr/include/c++/14/bits/regex.h:1485:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1485 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1485:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
/usr/include/c++/14/bits/regex.h:1560:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1560 |     operator<(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1560:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'const char [2]'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
/usr/include/c++/14/bits/regex.h:1660:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1660 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1660:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
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:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'const std::pair<_T1, _T2>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >= 13 ) return cout << a + b < endl,0;
      |                                              ^~~~
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/string_view:673:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  673 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:673:5: note:   template argument deduction/substitution failed:
a.cc:15:14: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   15 | #define endl "\n"
      |              ^~~~
a.cc:35:46: note: in expansion of macro 'endl'
   35 |         if( a >