Language: C++

#include <iostream>                                                                                                  using namespace std;                                                                                                                                                                                                                      int main(){                                                                                                                  string s;                                                                                                            cin >> s;                                                                                                                                                                                                                                 if(s=="ABC"){                                                                                                                cout <<"ARC" << endl;                                                                                        }else{                                                                                                                       cout <<"ABC" << endl;                                                                                        }                                                                                                            }    

Compiler output:
a.cc:1:118: warning: extra tokens at end of #include directive
    1 | #include <iostream>                                                                                                  using namespace std;                                                                                                                                                                                                                      int main(){                                                                                                                  string s;                                                                                                            cin >> s;                                                                                                                                                                                                                                 if(s=="ABC"){                                                                                                                cout <<"ARC" << endl;                                                                                        }else{                                                                                                                       cout <<"ABC" << endl;                                                                                        }                                                                                                            }
      |                                                                                                                      ^~~~~
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/14/../../../x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x17): undefined reference to `main'
collect2: error: ld returned 1 exit status