Language: C++

using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using System.Numerics;
using System.Diagnostics;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Runtime.CompilerServices;
using static System.Math;

class P
{
    static void Main()
    {
        int[] abk = Console.ReadLine().Split().Select(int.Parse).ToArray();
        Console.WriteLine(string.Join("\n", Enumerable.Range(abk[0], abk[2]).Concat(Enumerable.Range(abk[1] - abk[2] + 1, abk[2]).Where(x => abk[0] <= x || x <= abk[1]).Distinct().OrderBy(x => x)));
    }
}


Compiler output:
a.cc:1:7: error: expected nested-name-specifier before 'System'
    1 | using System;
      |       ^~~~~~
a.cc:2:7: error: expected nested-name-specifier before 'System'
    2 | using System.IO;
      |       ^~~~~~
a.cc:3:7: error: expected nested-name-specifier before 'System'
    3 | using System.Collections.Generic;
      |       ^~~~~~
a.cc:4:7: error: expected nested-name-specifier before 'System'
    4 | using System.Linq;
      |       ^~~~~~
a.cc:5:7: error: expected nested-name-specifier before 'System'
    5 | using System.Numerics;
      |       ^~~~~~
a.cc:6:7: error: expected nested-name-specifier before 'System'
    6 | using System.Diagnostics;
      |       ^~~~~~
a.cc:7:7: error: expected nested-name-specifier before 'System'
    7 | using System.Text;
      |       ^~~~~~
a.cc:8:7: error: expected nested-name-specifier before 'System'
    8 | using System.Text.RegularExpressions;
      |       ^~~~~~
a.cc:9:7: error: expected nested-name-specifier before 'System'
    9 | using System.Threading.Tasks;
      |       ^~~~~~
a.cc:10:7: error: expected nested-name-specifier before 'System'
   10 | using System.Runtime.CompilerServices;
      |       ^~~~~~
a.cc:11:7: error: expected nested-name-specifier before 'static'
   11 | using static System.Math;
      |       ^~~~~~
a.cc:20:2: error: expected ';' after class definition
   20 | }
      |  ^
      |  ;
a.cc: In static member function 'static void P::Main()':
a.cc:17:12: error: structured binding declaration cannot have type 'int'
   17 |         int[] abk = Console.ReadLine().Split().Select(int.Parse).ToArray();
      |            ^~
a.cc:17:12: note: type must be cv-qualified 'auto' or reference to cv-qualified 'auto'
a.cc:17:12: error: empty structured binding declaration
a.cc:17:15: error: expected initializer before 'abk'
   17 |         int[] abk = Console.ReadLine().Split().Select(int.Parse).ToArray();
      |               ^~~
a.cc:18:9: error: 'Console' was not declared in this scope
   18 |         Console.WriteLine(string.Join("\n", Enumerable.Range(abk[0], abk[2]).Concat(Enumerable.Range(abk[1] - abk[2] + 1, abk[2]).Where(x => abk[0] <= x || x <= abk[1]).Distinct().OrderBy(x => x)));
      |         ^~~~~~~
a.cc:18:27: error: 'string' was not declared in this scope
   18 |         Console.WriteLine(string.Join("\n", Enumerable.Range(abk[0], abk[2]).Concat(Enumerable.Range(abk[1] - abk[2] + 1, abk[2]).Where(x => abk[0] <= x || x <= abk[1]).Distinct().OrderBy(x => x)));
      |                           ^~~~~~
a.cc:18:45: error: 'Enumerable' was not declared in this scope
   18 |         Console.WriteLine(string.Join("\n", Enumerable.Range(abk[0], abk[2]).Concat(Enumerable.Range(abk[1] - abk[2] + 1, abk[2]).Where(x => abk[0] <= x || x <= abk[1]).Distinct().OrderBy(x => x)));
      |                                             ^~~~~~~~~~
a.cc:18:62: error: 'abk' was not declared in this scope
   18 |         Console.WriteLine(string.Join("\n", Enumerable.Range(abk[0], abk[2]).Concat(Enumerable.Range(abk[1] - abk[2] + 1, abk[2]).Where(x => abk[0] <= x || x <= abk[1]).Distinct().OrderBy(x => x)));
      |                                                              ^~~
a.cc:18:137: error: 'x' was not declared in this scope
   18 |         Console.WriteLine(string.Join("\n", Enumerable.Range(abk[0], abk[2]).Concat(Enumerable.Range(abk[1] - abk[2] + 1, abk[2]).Where(x => abk[0] <= x || x <= abk[1]).Distinct().OrderBy(x => x)));
      |                                                                                                                                         ^
a.cc:18:140: error: expected primary-expression before '>' token
   18 |         Console.WriteLine(string.Join("\n", Enumerable.Range(abk[0], abk[2]).Concat(Enumerable.Range(abk[1] - abk[2] + 1, abk[2]).Where(x => abk[0] <= x || x <= abk[1]).Distinct().OrderBy(x => x)));
      |                                                                                                                                            ^
a.cc:18:192: error: expected primary-expression before '>' token
   18 |         Console.WriteLine(string.Join("\n", Enumerable.Range(abk[0], abk[2]).Concat(Enumerable.Range(abk[1] - abk[2] + 1, abk[2]).Where(x => abk[0] <= x || x <= abk[1]).Distinct().OrderBy(x => x)));
      |                                                                                                                                                                                                ^