Language: C++

#include <bits/stdc++.h>
typedef ll long long
using namespace std;

int main(){
	ll l, r;
	cin >> l >> r;
	
	if(r-l >= 2019){
		cout << 0 << endl;
	}
	else{
		int ans = 2020;
		for(ll i= l; i<=r; i++){
			for(ll j=i+1; j<=r; j++){
				ans = min(ans, (i*j)%2019);
			}
		}
		
		cout << ans << endl;
	}
	
	
	return 0;
}

Compiler output:
a.cc:2:9: error: 'll' does not name a type
    2 | typedef ll long long
      |         ^~
a.cc: In function 'int main()':
a.cc:6:9: error: 'll' was not declared in this scope
    6 |         ll l, r;
      |         ^~
a.cc:7:9: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    7 |         cin >> l >> r;
      |         ^~~
      |         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:7:16: error: 'l' was not declared in this scope
    7 |         cin >> l >> r;
      |                ^
a.cc:7:21: error: 'r' was not declared in this scope
    7 |         cin >> l >> r;
      |                     ^
a.cc:10:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   10 |                 cout << 0 << 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:10:30: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   10 |                 cout << 0 << endl;
      |                              ^~~~
      |                              std::endl
In file included from /usr/include/c++/14/istream:41,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
a.cc:14:23: error: expected ';' before 'i'
   14 |                 for(ll i= l; i<=r; i++){
      |                       ^~
      |                       ;
a.cc:14:30: error: 'i' was not declared in this scope
   14 |                 for(ll i= l; i<=r; i++){
      |                              ^
a.cc:15:31: error: expected ';' before 'j'
   15 |                         for(ll j=i+1; j<=r; j++){
      |                               ^~
      |                               ;
a.cc:15:39: error: 'j' was not declared in this scope; did you mean 'jn'?
   15 |                         for(ll j=i+1; j<=r; j++){
      |                                       ^
      |                                       jn
a.cc:16:39: error: 'min' was not declared in this scope; did you mean 'std::min'?
   16 |                                 ans = min(ans, (i*j)%2019);
      |                                       ^~~
      |                                       std::min
In file included from /usr/include/c++/14/algorithm:61,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_algo.h:5696:5: note: 'std::min' declared here
 5696 |     min(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
a.cc:20:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   20 |                 cout << ans << 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:20:32: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   20 |                 cout << ans << endl;
      |                                ^~~~
      |                                std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~