Language: C++

#include <bits/stdc++.h>

int main(){
  int N; cin >> N;
  vector<int> S(N);
  for(int i = 0; i < N; ++i){
    cin>>S[i];
  }
  
  vector<int> M(N);
  for(int i = 0; i < N; ++i){
    if(i % 2 != 1){
      M[i] = 1;
    }
    else{
      M[i] = 0;
    }
  }
  
  vector<int> T(N);
  for(int i = 0; i < N; ++i){
    if(i % 2 != 1){
      T[i] = 0;
    }
    else{
      T[i] = 1;
    }
  }
  
  int mans; mans = 0;
  for(int i = 0; i < N; ++i){
    if(S[i] != M[i]){
      bool is_candidate = true;
    }
    else{
      is_candidate = false;
      break;
    }
  }
  if(is_candidate){
    ++mans;
  }
  
  int tans; tans = 0;
  for(int i = 0; i < N; ++i){
    if(S[i] != T[i]){
      bool is_candidate2 = true;
    }
    else{
      is_candidate2 = false;
      break;
    }
  }
  if(is_candidate2){
    ++tans;
  }
  
  int ans;
  if(mans <= tans){
    ans = mans;
  }
  else{
    ans = tans;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:4:10: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    4 |   int N; cin >> N;
      |          ^~~
      |          std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:5:3: error: 'vector' was not declared in this scope
    5 |   vector<int> S(N);
      |   ^~~~~~
a.cc:5:3: note: suggested alternatives:
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53:
/usr/include/c++/14/bits/stl_vector.h:428:11: note:   'std::vector'
  428 |     class vector : protected _Vector_base<_Tp, _Alloc>
      |           ^~~~~~
/usr/include/c++/14/vector:93:13: note:   'std::pmr::vector'
   93 |       using vector = std::vector<_Tp, polymorphic_allocator<_Tp>>;
      |             ^~~~~~
a.cc:5:10: error: expected primary-expression before 'int'
    5 |   vector<int> S(N);
      |          ^~~
a.cc:7:10: error: 'S' was not declared in this scope
    7 |     cin>>S[i];
      |          ^
a.cc:10:10: error: expected primary-expression before 'int'
   10 |   vector<int> M(N);
      |          ^~~
a.cc:13:7: error: 'M' was not declared in this scope
   13 |       M[i] = 1;
      |       ^
a.cc:16:7: error: 'M' was not declared in this scope
   16 |       M[i] = 0;
      |       ^
a.cc:20:10: error: expected primary-expression before 'int'
   20 |   vector<int> T(N);
      |          ^~~
a.cc:23:7: error: 'T' was not declared in this scope
   23 |       T[i] = 0;
      |       ^
a.cc:26:7: error: 'T' was not declared in this scope
   26 |       T[i] = 1;
      |       ^
a.cc:32:8: error: 'S' was not declared in this scope
   32 |     if(S[i] != M[i]){
      |        ^
a.cc:32:16: error: 'M' was not declared in this scope
   32 |     if(S[i] != M[i]){
      |                ^
a.cc:36:7: error: 'is_candidate' was not declared in this scope
   36 |       is_candidate = false;
      |       ^~~~~~~~~~~~
a.cc:40:6: error: 'is_candidate' was not declared in this scope
   40 |   if(is_candidate){
      |      ^~~~~~~~~~~~
a.cc:46:8: error: 'S' was not declared in this scope
   46 |     if(S[i] != T[i]){
      |        ^
a.cc:46:16: error: 'T' was not declared in this scope
   46 |     if(S[i] != T[i]){
      |                ^
a.cc:50:7: error: 'is_candidate2' was not declared in this scope
   50 |       is_candidate2 = false;
      |       ^~~~~~~~~~~~~
a.cc:54:6: error: 'is_candidate2' was not declared in this scope
   54 |   if(is_candidate2){
      |      ^~~~~~~~~~~~~