Language: C++

#include<string>
#include<vector>
#include<math.h>
#include<map>
using namespace std;
int main(void){
    string a,b;
    cin>>a>>b;
    if(a.size()>b.size()) cout<<"GREATER"<<endl;
    else if(a.size()<b.size()) cout<<"LESS"<<endl;
    else if(a>b) cout<<"GREATER"<<endl;
    else if(a<b) cout<<"LESS"<<endl;
    else if(a==b) cout<<"EQURL"<<endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:5: error: 'cin' was not declared in this scope
    8 |     cin>>a>>b;
      |     ^~~
a.cc:5:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
    4 | #include<map>
  +++ |+#include <iostream>
    5 | using namespace std;
a.cc:9:27: error: 'cout' was not declared in this scope
    9 |     if(a.size()>b.size()) cout<<"GREATER"<<endl;
      |                           ^~~~
a.cc:9:27: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:9:44: error: 'endl' was not declared in this scope
    9 |     if(a.size()>b.size()) cout<<"GREATER"<<endl;
      |                                            ^~~~
a.cc:5:1: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
    4 | #include<map>
  +++ |+#include <ostream>
    5 | using namespace std;
a.cc:10:32: error: 'cout' was not declared in this scope
   10 |     else if(a.size()<b.size()) cout<<"LESS"<<endl;
      |                                ^~~~
a.cc:10:32: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:10:46: error: 'endl' was not declared in this scope
   10 |     else if(a.size()<b.size()) cout<<"LESS"<<endl;
      |                                              ^~~~
a.cc:10:46: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:11:18: error: 'cout' was not declared in this scope
   11 |     else if(a>b) cout<<"GREATER"<<endl;
      |                  ^~~~
a.cc:11:18: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:11:35: error: 'endl' was not declared in this scope
   11 |     else if(a>b) cout<<"GREATER"<<endl;
      |                                   ^~~~
a.cc:11:35: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:12:18: error: 'cout' was not declared in this scope
   12 |     else if(a<b) cout<<"LESS"<<endl;
      |                  ^~~~
a.cc:12:18: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:12:32: error: 'endl' was not declared in this scope
   12 |     else if(a<b) cout<<"LESS"<<endl;
      |                                ^~~~
a.cc:12:32: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:13:19: error: 'cout' was not declared in this scope
   13 |     else if(a==b) cout<<"EQURL"<<endl;
      |                   ^~~~
a.cc:13:19: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:13:34: error: 'endl' was not declared in this scope
   13 |     else if(a==b) cout<<"EQURL"<<endl;
      |                                  ^~~~
a.cc:13:34: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'