Language: C++

#include<iostream>
#include<numeric>
#include<algorithm>
using namespace std;

int main(void){
    int N, K;
    cin >> N >> K;
    long long p[210000];
    int i;
    int Q[210000];
    long long A[210000];
    for(i=0; i<N; i++){
        cin >> p[i];
    }
    A[0]=accumulate(p, p+K, 0LL);
    for(i=1; i<N-K+1; i++){
        A[i] = A[i-1] - p[i-1] + p[K-1+i];
    }
    sort(A, A+N-K+1, greater<int>());
    cout << (static_cast<__float128>(A[0]) + static_cast<__float128>(K))*0.5 << endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:21:10: error: ambiguous overload for 'operator<<' (operand types are 'std::ostream' {aka 'std::basic_ostream<char>'} and '__float128')
   21 |     cout << (static_cast<__float128>(A[0]) + static_cast<__float128>(K))*0.5 << endl;
      |     ~~~~ ^~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |     |                                                                   |
      |     std::ostream {aka std::basic_ostream<char>}                         __float128
In file included from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/ostream:174:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  174 |       operator<<(long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:178:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  178 |       operator<<(unsigned long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:182:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  182 |       operator<<(bool __n)
      |       ^~~~~~~~
In file included from /usr/include/c++/14/ostream:1022:
/usr/include/c++/14/bits/ostream.tcc:96:5: note: candidate: 'std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char; _Traits = std::char_traits<char>]'
   96 |     basic_ostream<_CharT, _Traits>::
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/ostream:189:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  189 |       operator<<(unsigned short __n)
      |       ^~~~~~~~
/usr/include/c++/14/bits/ostream.tcc:110:5: note: candidate: 'std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char; _Traits = std::char_traits<char>]'
  110 |     basic_ostream<_CharT, _Traits>::
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/ostream:200:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  200 |       operator<<(unsigned int __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:211:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  211 |       operator<<(long long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:215:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  215 |       operator<<(unsigned long long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:231:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  231 |       operator<<(double __f)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:235:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  235 |       operator<<(float __f)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:243:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  243 |       operator<<(long double __f)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:573:5: note: candidate: 'std::basic_ostream<_CharT, _Traits>& std::operator<<(basic_ostream<_CharT, _Traits>&, char) [with _CharT = char; _Traits = char_traits<char>]'
  573 |     operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
      |     ^~~~~~~~
/usr/include/c++/14/ostream:579:5: note: candidate: 'std::basic_ostream<char, _Traits>& std::operator<<(basic_ostream<char, _Traits>&, char) [with _Traits = char_traits<char>]'
  579 |     operator<<(basic_ostream<char, _Traits>& __out, char __c)
      |     ^~~~~~~~
/usr/include/c++/14/ostream:590:5: note: candidate: 'std::basic_ostream<char, _Traits>& std::operator<<(basic_ostream<char, _Traits>&, signed char) [with _Traits = char_traits<char>]'
  590 |     operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
      |     ^~~~~~~~
/usr/include/c++/14/ostream:595:5: note: candidate: 'std::basic_ostream<char, _Traits>& std::operator<<(basic_ostream<char, _Traits>&, unsigned char) [with _Traits = char_traits<char>]'
  595 |     operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
      |     ^~~~~~~~