Language: C++

#include <iostream>
using namespace
  int main() {
  if (a==1) cout<<"NO";
if (a==2) cout<<"NO";
if (a==3) cout<<"YES";
  if (a==4) cout<<"NO";
  if (a==5) cout<<"YES";
  if (a==6) cout<<"NO";
  if (a==7) cout<<"YES";
  if (a==8) cout<<"NO";
  if (a==9) cout<<"NO";
  
  
  cout << endl;
  
}

Compiler output:
a.cc:3:3: error: expected identifier before 'int'
    3 |   int main() {
      |   ^~~
a.cc:2:16: error: expected ';' before 'int'
    2 | using namespace
      |                ^
      |                ;
    3 |   int main() {
      |   ~~~           
a.cc: In function 'int main()':
a.cc:4:7: error: 'a' was not declared in this scope
    4 |   if (a==1) cout<<"NO";
      |       ^
a.cc:4:13: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    4 |   if (a==1) cout<<"NO";
      |             ^~~~
      |             std::cout
In file included from a.cc:1:
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:5:5: error: 'a' was not declared in this scope
    5 | if (a==2) cout<<"NO";
      |     ^
a.cc:5:11: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    5 | if (a==2) cout<<"NO";
      |           ^~~~
      |           std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:6:5: error: 'a' was not declared in this scope
    6 | if (a==3) cout<<"YES";
      |     ^
a.cc:6:11: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    6 | if (a==3) cout<<"YES";
      |           ^~~~
      |           std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:7:7: error: 'a' was not declared in this scope
    7 |   if (a==4) cout<<"NO";
      |       ^
a.cc:7:13: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    7 |   if (a==4) cout<<"NO";
      |             ^~~~
      |             std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:8:7: error: 'a' was not declared in this scope
    8 |   if (a==5) cout<<"YES";
      |       ^
a.cc:8:13: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    8 |   if (a==5) cout<<"YES";
      |             ^~~~
      |             std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:9:7: error: 'a' was not declared in this scope
    9 |   if (a==6) cout<<"NO";
      |       ^
a.cc:9:13: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    9 |   if (a==6) cout<<"NO";
      |             ^~~~
      |             std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:10:7: error: 'a' was not declared in this scope
   10 |   if (a==7) cout<<"YES";
      |       ^
a.cc:10:13: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   10 |   if (a==7) cout<<"YES";
      |             ^~~~
      |             std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:11:7: error: 'a' was not declared in this scope
   11 |   if (a==8) cout<<"NO";
      |       ^
a.cc:11:13: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   11 |   if (a==8) cout<<"NO";
      |             ^~~~
      |             std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:12:7: error: 'a' was not declared in this scope
   12 |   if (a==9) cout<<"NO";
      |       ^
a.cc:12:13: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   12 |   if (a==9) cout<<"NO";
      |             ^~~~
      |             std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:15:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   15 |   cout << endl;
      |   ^~~~
      |   std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:15:11: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   15 |   cout << endl;
      |           ^~~~
      |           std::endl
In file included from /usr/include/c++/14/iostream:41:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~