answer.code:13:53: error: ‘int yn’ redeclared as different kind of entity
   13 | int i,j,l,t,n,x,y,a,b,c,aux,cnt,maxx,cost,x1,yy1,xn,yn,xi[108],yi[108],minn1,minn2,aux1,aux2,nr,poz,plus1,plus2;
      |                                                     ^~
In file included from /usr/include/features.h:461,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/os_defines.h:39,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/c++config.h:571,
                 from /usr/include/c++/11/cassert:43,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:33,
                 from answer.code:1:
/usr/include/x86_64-linux-gnu/bits/mathcalls.h:222:1: note: previous declaration ‘double yn(int, double)’
  222 | __MATHCALL (yn,, (int, _Mdouble_));
      | ^~~~~~~~~~
answer.code: In function ‘int main()’:
answer.code:21:12: error: no match for ‘operator>>’ (operand types are ‘std::basic_istream<char>::__istream_type’ {aka ‘std::basic_istream<char>’} and ‘double(int, double) throw ()’ {aka ‘double(int, double)’})
   21 |     cin>>xn>>yn;
      |     ~~~~~~~^~~~
      |        |     |
      |        |     double(int, double) throw () {aka double(int, double)}
      |        std::basic_istream<char>::__istream_type {aka std::basic_istream<char>}
In file included from /usr/include/c++/11/sstream:38,
                 from /usr/include/c++/11/complex:45,
                 from /usr/include/c++/11/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:54,
                 from answer.code:1:
/usr/include/c++/11/istream:120:7: note: candidate: ‘std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__istream_type& (*)(std::basic_istream<_CharT, _Traits>::__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]’ (near match)
  120 |       operator>>(__istream_type& (*__pf)(__istream_type&))
      |       ^~~~~~~~
/usr/include/c++/11/istream:120:7: note:   conversion of argument 1 would be ill-formed:
answer.code:21:14: error: invalid conversion from ‘double (*)(int, double) throw ()’ {aka ‘double (*)(int, double)’} to ‘std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&)’ {aka ‘std::basic_istream<char>& (*)(std::basic_istream<char>&)’} [-fpermissive]
   21 |     cin>>xn>>yn;
      |              ^~
      |              |
      |              double (*)(int, double) throw () {aka double (*)(int, double)}
In file included from /usr/include/c++/11/sstream:38,
                 from /usr/include/c++/11/complex:45,
                 from /usr/include/c++/11/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:54,
                 from answer.code:1:
/usr/include/c++/11/istream:124:7: note: candidate: ‘std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__ios_type& (*)(std::basic_istream<_CharT, _Traits>::__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>; std::basic_istream<_CharT, _Traits>::__ios_type = std::basic_ios<char>]’ (near match)
  124 |       operator>>(__ios_type& (*__pf)(__ios_type&))
      |       ^~~~~~~~
/usr/include/c++/11/istream:124:7: note:   conversion of argument 1 would be ill-formed:
answer.code:21:14: error: invalid conversion from ‘double (*)(int, double) throw ()’ {aka ‘double (*)(int, double)’} to ‘std::basic_istream<char>::__ios_type& (*)(std::basic_istream<char>::__ios_type&)’ {aka ‘std::basic_ios<char>& (*)(std::basic_ios<char>&)’} [-fpermissive]
   21 |     cin>>xn>>yn;
      |              ^~
      |              |
      |              double (*)(int, double) throw () {aka double (*)(int, double)}
In file included from /usr/include/c++/11/sstream:38,
                 from /usr/include/c++/11/complex:45,
                 from /usr/include/c++/11/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:54,
                 from answer.code:1:
/usr/include/c++/11/istream:131:7: note: candidate: ‘std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]’ (near match)
  131 |       operator>>(ios_base& (*__pf)(ios_base&))
      |       ^~~~~~~~
/usr/include/c++/11/istream:131:7: note:   conversion of argument 1 would be ill-formed:
answer.code:21:14: error: invalid conversion from ‘double (*)(int, double) throw ()’ {aka ‘double (*)(int, double)’} to ‘std::ios_base& (*)(std::ios_base&)’ [-fpermissive]
   21 |     cin>>xn>>yn;
      |              ^~
      |              |
    ...