Language: C++

#include <iostream>
#include <set>
using namespace std;
int main() {
 	 bool flag = true;
	int n, a, b;
	cin >> n;
  pair<int,int> s,u;
	int s[2][n];
	s[0][0] = 0;
	s[1][0] = 0;
	set< pair<int,int> > step;
	for(int i = 1; i <= n; i ++) {
		cin >> s[0][i] >> s[1][i];
	}
  s.front = s[0][1] - s[0][0];
  s.second = s[1][1] - s[1][0];
	for(int i = n; i > 0; i --) {
      u = make_pair(s[0][i] - s[0][i - 1], s[1][i] - s[1][i - 1]);
      if(u == i)
		step.insert();
	}
	cout << step.size() - 1 << endl;
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:13: error: conflicting declaration 'int s [2][n]'
    9 |         int s[2][n];
      |             ^
a.cc:8:17: note: previous declaration as 'std::pair<int, int> s'
    8 |   pair<int,int> s,u;
      |                 ^
a.cc:10:10: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   10 |         s[0][0] = 0;
      |          ^
a.cc:11:10: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   11 |         s[1][0] = 0;
      |          ^
a.cc:14:25: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   14 |                 cin >> s[0][i] >> s[1][i];
      |                         ^
a.cc:14:36: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   14 |                 cin >> s[0][i] >> s[1][i];
      |                                    ^
a.cc:16:5: error: 'struct std::pair<int, int>' has no member named 'front'
   16 |   s.front = s[0][1] - s[0][0];
      |     ^~~~~
a.cc:16:14: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   16 |   s.front = s[0][1] - s[0][0];
      |              ^
a.cc:16:24: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   16 |   s.front = s[0][1] - s[0][0];
      |                        ^
a.cc:17:15: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   17 |   s.second = s[1][1] - s[1][0];
      |               ^
a.cc:17:25: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   17 |   s.second = s[1][1] - s[1][0];
      |                         ^
a.cc:19:22: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   19 |       u = make_pair(s[0][i] - s[0][i - 1], s[1][i] - s[1][i - 1]);
      |                      ^
a.cc:19:32: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   19 |       u = make_pair(s[0][i] - s[0][i - 1], s[1][i] - s[1][i - 1]);
      |                                ^
a.cc:19:45: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   19 |       u = make_pair(s[0][i] - s[0][i - 1], s[1][i] - s[1][i - 1]);
      |                                             ^
a.cc:19:55: error: no match for 'operator[]' (operand types are 'std::pair<int, int>' and 'int')
   19 |       u = make_pair(s[0][i] - s[0][i - 1], s[1][i] - s[1][i - 1]);
      |                                                       ^
a.cc:20:12: error: no match for 'operator==' (operand types are 'std::pair<int, int>' and 'int')
   20 |       if(u == i)
      |          ~ ^~ ~
      |          |    |
      |          |    int
      |          std::pair<int, int>
In file included from /usr/include/c++/14/iosfwd:42,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/postypes.h:192:5: note: candidate: 'template<class _StateT> bool std::operator==(const fpos<_StateT>&, const fpos<_StateT>&)'
  192 |     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:192:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   'std::pair<int, int>' is not derived from 'const std::fpos<_StateT>'
   20 |       if(u == i)
      |               ^
In file included from /usr/include/c++/14/string:43,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44:
/usr/include/c++/14/bits/allocator.h:235:5: note: candidate: 'template<class _T1, class _T2> bool std::operator==(const allocator<_CharT>&, const allocator<_T2>&)'
  235 |     operator==(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/14/bits/allocator.h:235:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   'std::pair<int, int>' is not derived from 'const std::allocator<_CharT>'
   20 |       if(u == i)
      |               ^
In file included from /usr/include/c++/14/string:48:
/usr/include/c++/14/bits/stl_iterator.h:441:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  441 |     operator==(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:441:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   'std::pair<int, int>' is not derived from 'const std::reverse_iterator<_Iterator>'
   20 |       if(u == i)
      |               ^
/usr/include/c++/14/bits/stl_iterator.h:486:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  486 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   'std::pair<int, int>' is not derived from 'const std::reverse_iterator<_Iterator>'
   20 |       if(u == i)
      |               ^
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1667 |     operator==(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   'std::pair<int, int>' is not derived from 'const std::move_iterator<_IteratorL>'
   20 |       if(u == i)
      |               ^
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1737 |     operator==(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   'std::pair<int, int>' is not derived from 'const std::move_iterator<_IteratorL>'
   20 |       if(u == i)
      |               ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/string:51:
/usr/include/c++/14/bits/stl_pair.h:1033:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1033 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1033:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   mismatched types 'const std::pair<_T1, _T2>' and 'int'
   20 |       if(u == i)
      |               ^
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54:
/usr/include/c++/14/string_view:629:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  629 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:629:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   'std::pair<int, int>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   20 |       if(u == i)
      |               ^
/usr/include/c++/14/string_view:637:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  637 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:637:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   'std::pair<int, int>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   20 |       if(u == i)
      |               ^
/usr/include/c++/14/string_view:644:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  644 |     operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:644:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'int'
   20 |       if(u == i)
      |               ^
/usr/include/c++/14/bits/basic_string.h:3755:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3755 |     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3755:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   'std::pair<int, int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   20 |       if(u == i)
      |               ^
/usr/include/c++/14/bits/basic_string.h:3772:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3772 |     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3772:5: note:   template argument deduction/substitution failed:
a.cc:20:15: note:   'std::pair<int, int>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   20 |       if(u == i)
      |               ^
/usr/include/c++/14/bits/basic_string.h:3819:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator