Language: C++

#include<bits/stdc++.h>
#define vll vector<ll>
#define vi vector<int>
#define vpll vector<pair<ll,ll>>
#define pii pair<int,int>
#define REP(i,a) for(int (i)=0; (i)<(a); (i)++)
#define RREP(i,a) for(int (i)=a-1; (i)>=(0); (i)--)
#define REP2(i,a,b) for(int (i)=(a); (i)<(b); (i)++)
#define MOD 1000000007
#define ALL(v) v.begin(), v.end()
#define m0(x) memset(x,0,sizeof(x))
typedef long long ll;
typedef unsigned long long ull
using namespace std;
int main(){
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);

  ull n, k, ans = 0;
  cin >> n >> k;
  vector<ll> a(n);
  vector<ll> c(2001, 0);
  REP(i, n){
    cin >> a[i];
    c[a[i]]++;
  }
  ull x, y;
  REP(i, a.size()){
    x = 0; y = 0;
    REP(j,a.size()){
      if(a[j]<a[i] && j > i) y++;
      if(a[j]<a[i]) x++;
    }
    ans = ans + (k*y)%MOD + x*((k*k-1)%MOD)/2;
    ans%=MOD;
  }
  cout << ans << endl;
  return 0;
}

Compiler output:
a.cc:14:1: error: expected initializer before 'using'
   14 | using namespace std;
      | ^~~~~
a.cc: In function 'int main()':
a.cc:16:3: error: 'ios_base' has not been declared
   16 |   ios_base::sync_with_stdio(false);
      |   ^~~~~~~~
a.cc:17:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
   17 |   cin.tie(NULL);
      |   ^~~
      |   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:19:3: error: 'ull' was not declared in this scope; did you mean 'll'?
   19 |   ull n, k, ans = 0;
      |   ^~~
      |   ll
a.cc:20:10: error: 'n' was not declared in this scope; did you mean 'yn'?
   20 |   cin >> n >> k;
      |          ^
      |          yn
a.cc:20:15: error: 'k' was not declared in this scope
   20 |   cin >> n >> k;
      |               ^
a.cc:21:3: error: 'vector' was not declared in this scope
   21 |   vector<ll> a(n);
      |   ^~~~~~
a.cc:21:3: 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:21:12: error: expected primary-expression before '>' token
   21 |   vector<ll> a(n);
      |            ^
a.cc:21:14: error: 'a' was not declared in this scope
   21 |   vector<ll> a(n);
      |              ^
a.cc:22:12: error: expected primary-expression before '>' token
   22 |   vector<ll> c(2001, 0);
      |            ^
a.cc:22:14: error: 'c' was not declared in this scope
   22 |   vector<ll> c(2001, 0);
      |              ^
a.cc:27:6: error: expected ';' before 'x'
   27 |   ull x, y;
      |      ^~
      |      ;
a.cc:29:5: error: 'x' was not declared in this scope
   29 |     x = 0; y = 0;
      |     ^
a.cc:29:12: error: 'y' was not declared in this scope
   29 |     x = 0; y = 0;
      |            ^
a.cc:34:5: error: 'ans' was not declared in this scope; did you mean 'abs'?
   34 |     ans = ans + (k*y)%MOD + x*((k*k-1)%MOD)/2;
      |     ^~~
      |     abs
a.cc:37:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   37 |   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:37:11: error: 'ans' was not declared in this scope; did you mean 'abs'?
   37 |   cout << ans << endl;
      |           ^~~
      |           abs
a.cc:37:18: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   37 |   cout << ans << 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)
      |     ^~~~