answer
#include<bits/stdc++.h>
#define eps 1e-7
using namespace std;
int dp[5010][5010],n,h[5010],ans;
#define seek(p,a,b) ((double)(1)*(h[p]-h[a])/(p-a)>(double)(1)*(h[p]-h[b])/(p-b))
signed main(){
    ios::sync_with_stdio(false);
    cin.tie();cout.tie();
    cin>>n;
    for(int i=1;i<=n;i++)cin>>h[i];
	for(int i=1;i<=n;i++){
		dp[i][i]=1;ans^=1;
		int sigm=1,lst=0;
		for(int j=i-1;j>=1;j--){
			if(!lst)lst=j;
			else if(seek(i,lst,j))
				sigm+=min(dp[j+1][lst],dp[j+1][lst-1]),lst=j;
			dp[j][i]=sigm+min(dp[j][lst],dp[j][lst-1]);
			ans^=dp[j][i];
		}
	}
	cout<<ans<<'\n';
    return 0;
}

answer.code:1:1: error: ‘answer’ does not name a type
    1 | answer
      | ^~~~~~
In file included from /usr/include/c++/13/bits/stl_algobase.h:62,
                 from /usr/include/c++/13/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:51,
                 from answer.code:2:
/usr/include/c++/13/ext/type_traits.h:164:35: error: ‘constexpr const bool __gnu_cxx::__is_null_pointer’ redeclared as different kind of entity
  164 |   __is_null_pointer(std::nullptr_t)
      |                                   ^
/usr/include/c++/13/ext/type_traits.h:159:5: note: previous declaration ‘template<class _Type> constexpr bool __gnu_cxx::__is_null_pointer(_Type)’
  159 |     __is_null_pointer(_Type)
      |     ^~~~~~~~~~~~~~~~~
/usr/include/c++/13/ext/type_traits.h:164:26: error: ‘nullptr_t’ is not a member of ‘std’; did you mean ‘nullptr_t’?
  164 |   __is_null_pointer(std::nullptr_t)
      |                          ^~~~~~~~~
In file included from /usr/include/c++/13/cstddef:50,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:41:
/usr/lib/gcc/x86_64-linux-gnu/13/include/stddef.h:443:29: note: ‘nullptr_t’ declared here
  443 |   typedef decltype(nullptr) nullptr_t;
      |                             ^~~~~~~~~
In file included from /usr/include/c++/13/bits/stl_pair.h:60,
                 from /usr/include/c++/13/bits/stl_algobase.h:64:
/usr/include/c++/13/type_traits:510:31: error: ‘std::size_t’ has not been declared
  510 |   template<typename _Tp, std::size_t _Size>
      |                               ^~~~~~
/usr/include/c++/13/type_traits:511:25: error: ‘_Size’ was not declared in this scope
  511 |     struct is_array<_Tp[_Size]>
      |                         ^~~~~
/usr/include/c++/13/type_traits:511:31: error: template argument 1 is invalid
  511 |     struct is_array<_Tp[_Size]>
      |                               ^
/usr/include/c++/13/type_traits:617:33: error: ‘nullptr_t’ is not a member of ‘std’; did you mean ‘nullptr_t’?
  617 |     struct is_null_pointer<std::nullptr_t>
      |                                 ^~~~~~~~~
/usr/lib/gcc/x86_64-linux-gnu/13/include/stddef.h:443:29: note: ‘nullptr_t’ declared here
  443 |   typedef decltype(nullptr) nullptr_t;
      |                             ^~~~~~~~~
/usr/include/c++/13/type_traits:617:33: error: ‘nullptr_t’ is not a member of ‘std’; did you mean ‘nullptr_t’?
  617 |     struct is_null_pointer<std::nullptr_t>
      |                                 ^~~~~~~~~
/usr/lib/gcc/x86_64-linux-gnu/13/include/stddef.h:443:29: note: ‘nullptr_t’ declared here
  443 |   typedef decltype(nullptr) nullptr_t;
      |                             ^~~~~~~~~
/usr/include/c++/13/type_traits:617:42: error: template argument 1 is invalid
  617 |     struct is_null_pointer<std::nullptr_t>
      |                                          ^
/usr/include/c++/13/type_traits:621:48: error: template argument 1 is invalid
  621 |     struct is_null_pointer<const std::nullptr_t>
      |                                                ^
/usr/include/c++/13/type_traits:625:51: error: template argument 1 is invalid
  625 |     struct is_null_pointer<volatile std::nullptr_t>
      |                                                   ^
/usr/include/c++/13/type_traits:629:57: error: template argument 1 is invalid
  629 |     struct is_null_pointer<const volatile std::nullptr_t>
      |                                                         ^
/usr/include/c++/13/type_traits:1348:37: error: ‘size_t’ is not a member of ‘std’; did you mean ‘size_t’?
 1348 |     : public integral_constant<std::size_t, alignof(_Tp)>
      |                                     ^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/13/include/stddef.h:214:23: note: ‘size_t’ declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/13/type_traits:1348:37: error: ‘size_t’ is not a member of ‘std’; did you mean ‘size_t’?
 1348 |     : public integral_constant<std::size_t, alignof(_Tp)>
      |                                     ^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/13/include/stddef.h:214:23: note: ‘size_t’ declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/13/type_traits:1348:57: error: template argument 1 is invalid
 1348 |     : public integral_constant<std::size_t, alignof(_Tp)>
      |                                                         ^
/usr/include/c++/13/type_traits:1348:57: note: invalid template non-type parameter
/usr/include/c++/13/type_traits:1357:37: error: ‘size_t’ is not a member of ‘std’; did you mean ‘size_t’?
 1357 |     : public integral_constant<std::size_t, 0> { };
      |                                     ^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/13/include/stddef.h:214:23: note: ‘size_t’ declared here
  214 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
/usr/include/c++/13/type_traits:1357:37: error: ‘size_t’ is not a member ...