Language: C++

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

using db = double;
const db eps = 1e-6;

struct poi {
	db x, y;
	void r() { cin >> x >> y; }
	poi operator -(poi p) {
		return {x - p.x, y - p.y};
	}
	db cross(poi p) {
		return x * p.y - y * p.x;
	}
};
db xmul(poi a, poi b, poi c) {
	return (b - a).cross(c - a);
}

int main() {
	ios :: sync_with_stdio(false);
	poi a, b, c, p;
	while(cin >> a.x >> a.y) {
		b.r(); c.r(); p.r();
		poi s = abs(xmul(a, b, c));
		poi t = abs(xmul(p, a, b)) + abs(xmul(p, b, c)) + abs(xmul(p, c, a));
		if(s < t + eps && t < s + eps)
			cout << "YES\n";
		else
			cout << "NO\n";
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:26:28: error: conversion from 'double' to non-scalar type 'poi' requested
   26 |                 poi s = abs(xmul(a, b, c));
      |                         ~~~^~~~~~~~~~~~~~~
a.cc:27:65: error: conversion from 'double' to non-scalar type 'poi' requested
   27 |                 poi t = abs(xmul(p, a, b)) + abs(xmul(p, b, c)) + abs(xmul(p, c, a));
      |                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
a.cc:28:26: error: no match for 'operator+' (operand types are 'poi' and 'const db' {aka 'const double'})
   28 |                 if(s < t + eps && t < s + eps)
      |                        ~ ^ ~~~
      |                        |   |
      |                        poi const db {aka const double}
In file included from /usr/include/c++/14/bits/stl_algobase.h:67,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_iterator.h:627:5: note: candidate: 'template<class _Iterator> constexpr std::reverse_iterator<_Iterator> std::operator+(typename reverse_iterator<_Iterator>::difference_type, const reverse_iterator<_Iterator>&)'
  627 |     operator+(typename reverse_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:627:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'const db' {aka 'const double'}
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note: candidate: 'template<class _Iterator> constexpr std::move_iterator<_IteratorL> std::operator+(typename move_iterator<_IteratorL>::difference_type, const move_iterator<_IteratorL>&)'
 1798 |     operator+(typename move_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'const db' {aka 'const double'}
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
In file included 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/bits/basic_string.h:3598:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3598 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3598:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   'poi' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3616:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3616 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3616:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   mismatched types 'const _CharT*' and 'poi'
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3635:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3635 |     operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3635:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'const db' {aka 'const double'}
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3652:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3652 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3652:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   'poi' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3670:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
 3670 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, _CharT __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3670:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   'poi' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3682:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3682 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3682:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   'poi' is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3689:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3689 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3689:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   'poi' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3696:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3696 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3696:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   'poi' is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3719:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3719 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3719:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   mismatched types 'const _CharT*' and 'poi'
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3726:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3726 |     operator+(_CharT __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3726:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'const db' {aka 'const double'}
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3733:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const _CharT*)'
 3733 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3733:5: note:   template argument deduction/substitution failed:
a.cc:28:28: note:   'poi' is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   28 |                 if(s < t + eps && t < s + eps)
      |                            ^~~
/usr/include/c++/14/bits/basic_string.h:3740:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, _CharT)'
 3740 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3740:5: note:   template argument deduction/substit