Language: C++

#pragma comment(linker, "/stack:20000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx")

#include<bits/stdc++.h>
/*#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include<ext/pb_ds/detail/standard_policies.hpp>*/

#define sz(s) (int)(s.size())
#define all(s) s.begin(), s.end()
#define rep(a, b, c) for(int a = b; a <= c; ++a)
#define per(a, b, c) for(int a = b; a >= c; --a)
#define _ ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

using namespace std;
//using namespace __gnu_pbds;

typedef unsigned long long ull;
typedef long long ll;
/*typedef tree<pair<int, int>, 
null_type, less<pair<int, int>>, 
rb_tree_tag, tree_order_statistics_node_update>
ordered_set;*/
//find_by_order() order_of_key()

const double eps = 1e-7;
const int mod = 1e9+7, MXN = 5e5+17;
const int dx[] = {0,0,1,-1}, dy[] = {1,-1,0,0};

template<typename T>inline bool updmin(T &a, const T &b) {return a > b ? a = b,1 : 0;}
template<typename T>inline bool updmax(T &a, const T &b) {return a < b ? a = b,1 : 0;}

int32_t main() { _
#ifdef DanQQQQQ
	freopen(".in","r",stdin);
	freopen(".out","w",stdout);
#endif
	int n; cin >> n;
	cout << n*(n+1)>>1;
	return 0;
}

Compiler output:
a.cc: In function 'int32_t main()':
a.cc:40:24: error: no match for 'operator>>' (operand types are 'std::basic_ostream<char>' and 'int')
   40 |         cout << n*(n+1)>>1;
      |         ~~~~~~~~~~~~~~~^~~
      |              |           |
      |              |           int
      |              std::basic_ostream<char>
a.cc:40:24: note: candidate: 'operator>>(int, int)' (built-in)
   40 |         cout << n*(n+1)>>1;
      |         ~~~~~~~~~~~~~~~^~~
a.cc:40:24: note:   no known conversion for argument 1 from 'std::basic_ostream<char>' to 'int'
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:41,
                 from a.cc:5:
/usr/include/c++/14/cstddef:131:5: note: candidate: 'template<class _IntegerType> constexpr std::__byte_op_t<_IntegerType> std::operator>>(byte, _IntegerType)'
  131 |     operator>>(byte __b, _IntegerType __shift) noexcept
      |     ^~~~~~~~
/usr/include/c++/14/cstddef:131:5: note:   template argument deduction/substitution failed:
a.cc:40:14: note:   cannot convert 'std::cout.std::basic_ostream<char>::operator<<((n * (n + 1)))' (type 'std::basic_ostream<char>') to type 'std::byte'
   40 |         cout << n*(n+1)>>1;
      |         ~~~~~^~~~~~~~~~
In file included from /usr/include/c++/14/string:55,
                 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/basic_string.tcc:835:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
  835 |     operator>>(basic_istream<_CharT, _Traits>& __in,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.tcc:835:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<_CharT, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/bitset:1597:5: note: candidate: 'template<class _CharT, class _Traits, long unsigned int _Nb> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, bitset<_Nb>&)'
 1597 |     operator>>(std::basic_istream<_CharT, _Traits>& __is, bitset<_Nb>& __x)
      |     ^~~~~~~~
/usr/include/c++/14/bitset:1597:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<_CharT, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
In file included from /usr/include/c++/14/istream:1109,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/bits/istream.tcc:978:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _CharT&)'
  978 |     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c)
      |     ^~~~~~~~
/usr/include/c++/14/bits/istream.tcc:978:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<_CharT, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/istream:849:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, unsigned char&)'
  849 |     operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
      |     ^~~~~~~~
/usr/include/c++/14/istream:849:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<char, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/istream:854:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, signed char&)'
  854 |     operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
      |     ^~~~~~~~
/usr/include/c++/14/istream:854:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<char, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/istream:896:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _CharT*)'
  896 |     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:896:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<_CharT, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/istream:939:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, unsigned char*)'
  939 |     operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:939:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<char, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/istream:945:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, signed char*)'
  945 |     operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:945:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<char, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/istream:1099:5: note: candidate: 'template<class _Istream, class _Tp> _Istream&& std::operator>>(_Istream&&, _Tp&&)'
 1099 |     operator>>(_Istream&& __is, _Tp&& __x)
      |     ^~~~~~~~
/usr/include/c++/14/istream:1099:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/istream: In substitution of 'template<class _Istream, class _Tp> _Istream&& std::operator>>(_Istream&&, _Tp&&) [with _Istream = std::basic_ostream<char>&; _Tp = int]':
a.cc:40:19:   required from here
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/istream:1099:5: error: no type named 'type' in 'struct std::enable_if<false, void>'
 1099 |     operator>>(_Istream&& __is, _Tp&& __x)
      |     ^~~~~~~~
/usr/include/c++/14/complex:509:5: note: candidate: 'template<class _Tp, class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, complex<_Tp>&)'
  509 |     operator>>(basic_istream<_CharT, _Traits>& __is, complex<_Tp>& __x)
      |     ^~~~~~~~
/usr/include/c++/14/complex:509:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<_CharT, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:143:
/usr/include/c++/14/iomanip:76:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Resetiosflags)'
   76 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Resetiosflags __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:76:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<_CharT, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/iomanip:106:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Setiosflags)'
  106 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Setiosflags __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:106:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<_CharT, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/iomanip:137:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Setbase)'
  137 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Setbase __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:137:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<_CharT, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/iomanip:177:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Setfill<_CharT>)'
  177 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Setfill<_CharT> __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:177:5: note:   template argument deduction/substitution failed:
a.cc:40:26: note:   'std::basic_ostream<char>' is not derived from 'std::basic_istream<_CharT, _Traits>'
   40 |         cout << n*(n+1)>>1;
      |                          ^
/usr/include/c++/14/iomanip:207:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Setprecision)'
  207 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Setprecision __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:207:5: note:   template argument deduction/substitution failed:
a