Language: C++

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace A__Can_tbWate_for_Holiday
{
    class Program
    {
        static void Main(string[] args)
        {
            string SUN = "SUN";
            string MON = "MON";
            string TUE = "TUE";
            string WED = "WED";
            string THU = "THU";
            string FRI = "FRI";
            string SAT = "SAT";

            var today = Console.ReadLine();
            if (today == SUN)
            {
                Console.WriteLine(7);
            }
            else if (today == MON)
            {
                Console.WriteLine(6);
            }
            else if (today == TUE)
            {
                Console.WriteLine(5);
            }
            else if (today == WED)
            {
                Console.WriteLine(4);
            }
           else  if (today == THU)
            {
                Console.WriteLine(3);
            }
            else if (today == FRI)
            {
                Console.WriteLine(2);
            }
            else if (today == SAT)
            {
                Console.WriteLine(1);
            }
            Console.ReadKey();
        }
    }
}


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.Collections.Generic;
      |       ^~~~~~
a.cc:3:7: error: expected nested-name-specifier before 'System'
    3 | using System.Linq;
      |       ^~~~~~
a.cc:4:7: error: expected nested-name-specifier before 'System'
    4 | using System.Text;
      |       ^~~~~~
a.cc:5:7: error: expected nested-name-specifier before 'System'
    5 | using System.Threading.Tasks;
      |       ^~~~~~
a.cc:11:26: error: 'string' has not been declared
   11 |         static void Main(string[] args)
      |                          ^~~~~~
a.cc:11:35: error: expected ',' or '...' before 'args'
   11 |         static void Main(string[] args)
      |                                   ^~~~
a.cc:52:6: error: expected ';' after class definition
   52 |     }
      |      ^
      |      ;
a.cc: In static member function 'static void A__Can_tbWate_for_Holiday::Program::Main(int*)':
a.cc:13:13: error: 'string' was not declared in this scope
   13 |             string SUN = "SUN";
      |             ^~~~~~
a.cc:14:20: error: expected ';' before 'MON'
   14 |             string MON = "MON";
      |                    ^~~
a.cc:15:20: error: expected ';' before 'TUE'
   15 |             string TUE = "TUE";
      |                    ^~~
a.cc:16:20: error: expected ';' before 'WED'
   16 |             string WED = "WED";
      |                    ^~~
a.cc:17:20: error: expected ';' before 'THU'
   17 |             string THU = "THU";
      |                    ^~~
a.cc:18:20: error: expected ';' before 'FRI'
   18 |             string FRI = "FRI";
      |                    ^~~
a.cc:19:20: error: expected ';' before 'SAT'
   19 |             string SAT = "SAT";
      |                    ^~~
a.cc:21:13: error: 'var' was not declared in this scope
   21 |             var today = Console.ReadLine();
      |             ^~~
a.cc:22:17: error: 'today' was not declared in this scope
   22 |             if (today == SUN)
      |                 ^~~~~
a.cc:22:26: error: 'SUN' was not declared in this scope
   22 |             if (today == SUN)
      |                          ^~~
a.cc:24:17: error: 'Console' was not declared in this scope
   24 |                 Console.WriteLine(7);
      |                 ^~~~~~~
a.cc:26:31: error: 'MON' was not declared in this scope
   26 |             else if (today == MON)
      |                               ^~~
a.cc:28:17: error: 'Console' was not declared in this scope
   28 |                 Console.WriteLine(6);
      |                 ^~~~~~~
a.cc:30:31: error: 'TUE' was not declared in this scope
   30 |             else if (today == TUE)
      |                               ^~~
a.cc:32:17: error: 'Console' was not declared in this scope
   32 |                 Console.WriteLine(5);
      |                 ^~~~~~~
a.cc:34:31: error: 'WED' was not declared in this scope
   34 |             else if (today == WED)
      |                               ^~~
a.cc:36:17: error: 'Console' was not declared in this scope
   36 |                 Console.WriteLine(4);
      |                 ^~~~~~~
a.cc:38:31: error: 'THU' was not declared in this scope
   38 |            else  if (today == THU)
      |                               ^~~
a.cc:40:17: error: 'Console' was not declared in this scope
   40 |                 Console.WriteLine(3);
      |                 ^~~~~~~
a.cc:42:31: error: 'FRI' was not declared in this scope
   42 |             else if (today == FRI)
      |                               ^~~
a.cc:44:17: error: 'Console' was not declared in this scope
   44 |                 Console.WriteLine(2);
      |                 ^~~~~~~
a.cc:46:31: error: 'SAT' was not declared in this scope
   46 |             else if (today == SAT)
      |                               ^~~
a.cc:48:17: error: 'Console' was not declared in this scope
   48 |                 Console.WriteLine(1);
      |                 ^~~~~~~
a.cc:50:13: error: 'Console' was not declared in this scope
   50 |             Console.ReadKey();
      |             ^~~~~~~