Language: C++

#include <iostream>
#include <iomanip>
#include <complex>
#include <vector>
#include <cassert>
#include <algorithm>
#include <cmath>
#include <queue>
#include <utility>
using namespace std;
 
//num
const double EPS = 1e-10;
const double INF = 1e12;
#define X real()
#define Y imag()
#define LE(n,m) ((n) < (m) + EPS)
#define GE(n,m) ((n) + EPS > (m))
#define EQ(n,m) (abs((n)-(m)) < EPS)
 
// point, line, circle
typedef complex<double> P;
typedef vector<P> VP;
struct C{
    P p;
    double r;
    C(const P& p, const double& r) : p(p), r(r) {}
};
namespace std{
    bool operator < (const P& a, const P& b){
        return (a.X != b.X)? a.X < b.X : a.Y < b.Y;
    }
}
 
// vector operation
double dot(P a, P b){
    return (conj(a)*b).X;
}
double cross(P a, P b){
    return (conj(a)*b).Y;
}
 
//utility
int ccw(P a, P b, P c){
    b -= a;
    c -= a;
    if(cross(b,c) > EPS) return +1; //counter clockwise
    if(cross(b,c) <-EPS) return -1; //clockwise
    if(dot(b,c) < EPS) return +2; //c-a-b
    if(norm(b) < norm(c)) return -2; //a-b-c
    return 0; //a-c-b
}

int main(){
  vector<P> v(3);
  for(int i=0; i<3; i++){
    cin >> v[i].X >> v[i].Y;
  }

  vector<double> len(3);
  vector<double> angle(3);
  for(int i=0; i<3; i++){
    len[i] = abs(v[(i+1)%3]-v[(i+2)%3]);
    P e1 = v[(i+1)%3]-v[i];
    P e2 = v[(i+2)%3]-v[i];
    angle[i] = tan( acos( dot(e1,e2)/(abs(e1)*abs(e2)) ) *0.5 );
  }
  
  double ans=0;
  for(int i=0; i<3; i++){
    ans = max(ans, len[i]/(2.0 +(1/angle[(i+1)%3]) +(1/angle[(i+2)%3])) );
  }

  cout << fixed;
  cout << setprecision(11);
  cout << ans << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:57:9: error: no match for 'operator>>' (operand types are 'std::istream' {aka 'std::basic_istream<char>'} and 'double')
   57 |     cin >> v[i].X >> v[i].Y;
      |     ~~~ ^~
      |     |
      |     std::istream {aka std::basic_istream<char>}
In file included from /usr/include/c++/14/iostream:42,
                 from a.cc:1:
/usr/include/c++/14/istream:170:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  170 |       operator>>(bool& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:170:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'bool&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:174:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  174 |       operator>>(short& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:174:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'short int&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:177:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  177 |       operator>>(unsigned short& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:177:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'short unsigned int&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:181:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  181 |       operator>>(int& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:181:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'int&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:184:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  184 |       operator>>(unsigned int& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:184:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'unsigned int&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:188:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  188 |       operator>>(long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:188:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'long int&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:192:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  192 |       operator>>(unsigned long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:192:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'long unsigned int&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:199:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  199 |       operator>>(long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:199:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'long long int&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:203:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  203 |       operator>>(unsigned long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:203:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'long long unsigned int&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:219:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(float&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  219 |       operator>>(float& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:219:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'float&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:223:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(double&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  223 |       operator>>(double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:223:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'double&' to an rvalue of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:227:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long double&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  227 |       operator>>(long double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:227:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:15: error: cannot bind non-const lvalue reference of type 'long double&' to a value of type 'double'
   15 | #define X real()
      |               ^
a.cc:57:17: note: in expansion of macro 'X'
   57 |     cin >> v[i].X >> v[i].Y;
      |                 ^
/usr/include/c++/14/istream:328:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(void*&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]'
  328 |       operator>>(void*& __p)
      |       ^~~~~~~~
/usr/include/c++/14/istream:328:25: note:   no known conversion for argument 1 from 'double' to 'void*&'
  328 |       operator>>(void*& __p)
      |                  ~~~~~~~^~~
/usr/include/c++/14/istream:122:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__istream_type& (*)(__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]'
  122 |       operator>>(__istream_type& (*__pf)(__istream_type&))
      |       ^~~~~~~~
/usr/include/c++/14/istream:122:36: note:   no known conversion for argument 1 from 'double' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&)' {aka 'std::basic_istream<char>& (*)(std::basic_istream<char>&)'}
  122 |       operator>>(__istream_type& (*__pf)(__istream_type&))
      |                  ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/istream:126:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__ios_type& (*)(__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>; __ios_type = std::basic_ios<char>]'
  126 |       operator>>(__ios_type& (*_