Language: C++

#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <cctype>
#include <cmath>
#include <map>
#include <set>
#define rep(i, m, n) for(int i = m;i < n;i++)
#define repr(i, n) for(int i = n;i >= 0;i--)
#define ll long long
#define ull unsigned long long
#define push(a) push_back(a)
#define pop(a) pop_back(a)
#define debug(x) cout<<#x<<": "<<x<<endl
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define INF 999999999
using namespace std;
typedef pair<int, int> P;
typedef pair<ll, ll> LP;
typedef pair<int, P> PP;
typedef pair<ll, LP> LPP;

int dy[]={0, 0, 1, -1, 0};
int dx[]={1, -1, 0, 0, 0};

int main(){
    ull n,a,b[100001]={},ans=1;
    
    cin>>n;
    rep(i,0,n){
        cin>>b;
        a[b]++;
    }
    if(n%2==0){
        rep(i,0,100001){
            if(a[i]%2==0)ans*=2;
        }
    }else{
        if(a[0]%2==0){
            ans=0;
        }else{
           rep(i,0,100001){
            if(a[i]%2==0)ans*=2;
            } 
        }
    }
    cout<<ans<<endl;
    
}

Compiler output:
a.cc: In function 'int main()':
a.cc:35:12: error: no match for 'operator>>' (operand types are 'std::istream' {aka 'std::basic_istream<char>'} and 'long long unsigned int [100001]')
   35 |         cin>>b;
      |         ~~~^~~
      |         |    |
      |         |    long long unsigned int [100001]
      |         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:35:14: error: cannot bind non-const lvalue reference of type 'bool&' to a value of type 'long long unsigned int*'
   35 |         cin>>b;
      |              ^
/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:35:14: error: invalid conversion from 'long long unsigned int*' to 'short int' [-fpermissive]
   35 |         cin>>b;
      |              ^
      |              |
      |              long long unsigned int*
a.cc:35:14: error: cannot bind rvalue '(short int)((long long unsigned int*)(& b))' to 'short int&'
/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:35:14: error: invalid conversion from 'long long unsigned int*' to 'short unsigned int' [-fpermissive]
   35 |         cin>>b;
      |              ^
      |              |
      |              long long unsigned int*
a.cc:35:14: error: cannot bind rvalue '(short unsigned int)((long long unsigned int*)(& b))' to 'short unsigned int&'
/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:35:14: error: invalid conversion from 'long long unsigned int*' to 'int' [-fpermissive]
   35 |         cin>>b;
      |              ^
      |              |
      |              long long unsigned int*
a.cc:35:14: error: cannot bind rvalue '(int)((long long unsigned int*)(& b))' to 'int&'
/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:35:14: error: invalid conversion from 'long long unsigned int*' to 'unsigned int' [-fpermissive]
   35 |         cin>>b;
      |              ^
      |              |
      |              long long unsigned int*
a.cc:35:14: error: cannot bind rvalue '(unsigned int)((long long unsigned int*)(& b))' to 'unsigned int&'
/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:35:14: error: invalid conversion from 'long long unsigned int*' to 'long int' [-fpermissive]
   35 |         cin>>b;
      |              ^
      |              |
      |              long long unsigned int*
a.cc:35:14: error: cannot bind rvalue '(long int)((long long unsigned int*)(& b))' to 'long int&'
/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:35:14: error: invalid conversion from 'long long unsigned int*' to 'long unsigned int' [-fpermissive]
   35 |         cin>>b;
      |              ^
      |              |
      |              long long unsigned int*
a.cc:35:14: error: cannot bind rvalue '(long unsigned int)((long long unsigned int*)(& b))' to 'long unsigned int&'
/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:35:14: error: invalid conversion from 'long long unsigned int*' to 'long long int' [-fpermissive]
   35 |         cin>>b;
      |              ^
      |              |
      |              long long unsigned int*
a.cc:35:14: error: cannot bind rvalue '(long long int)((long long unsigned int*)(& b))' to 'long long int&'
/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:35:14: error: invalid conversion from 'long long unsigned int*' to 'long long unsigned int' [-fpermissive]
   35 |         cin>>b;
      |              ^
      |              |
      |              long long unsigned int*
a.cc:35:14: error: cannot bind rvalue '(long long unsigned int)((long long unsigned int*)(& b))' to 'long long unsigned int&'
/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>]' (near match)
  328 |       operator>>(void*& __p)
      |       ^~~~~~~~
/usr/include/c++/14/istream:328:7: note:   conversion of argument 1 would be ill-formed:
a.cc:35:14: error: cannot bind non-const lvalue reference of type 'void*&' to an rvalue of type 'void*'
   35 |         cin>>b;
      |              ^
/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>]'
  219 |       operator>>(float& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:219:25: note:   no known conversion for argument 1 from 'long long unsigned int [100001]' to 'float&'
  219 |       operator>>(float& __f)
      |                  ~~~~~~~^~~
/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>]'
  223 |       operator>>(double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:223:26: note:   no known conversion for argument 1 from 'long long unsigned int [100001]' to 'double&'
  223 |       operator>>(double& __f)
      |                  ~~~~~~~~^~~
/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>]'
  227 |       operator>>(long double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:227:31: note:   no known conversion for argument 1 from 'long long unsigned int [100001]' to 'long double&'
  227 |       operator>>(long double& __f)
      |                  ~~~~~~~~~~~~~^~~
/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 'long long unsigned int [100001]' 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::