Language: C++

using System;
using System.Linq;
using System.Collections.Generic;

class Program
{
    struct Connection {
        public List<long> list;
        public Connection(int index)
        {
            list = new List<long>();
        }
    }
    
    static void Main()
    {
        var nk = Console.ReadLine().Split(' ').Select(x => Int64.Parse(x)).ToArray();
        var N = nk[0];
        var K = nk[1];

        var connection = new Connection[N];
        for (int i = 0; i < N; ++i) connection[i] = new Connection(i);
        for (int i=0;i<N-1;++i)
        {
            var ab = Console.ReadLine().Split(' ').Select(x => Int64.Parse(x)).ToArray();
            connection[ab[0] - 1].list.Add(ab[1]-1);
            connection[ab[1] - 1].list.Add(ab[0] - 1);
        }

        var combination = new long[N];
        combination[0] = K;
        var queue = new Queue<long[]>();
        queue.Enqueue(new long[2] { -1, 0 });
        while (0 < queue.Count)
        {
            var current = queue.Dequeue();
            var parent = current[0];
            var node = current[1];
            var k = parent < 0 ? K - 1 : K - 2;
            foreach (var l in connection[node].list)
            {
                if (l == parent) continue;
                combination[l] = k;
                k--;
                queue.Enqueue(new long[2] { node, l });
            }
        }

        var ans = 1L;
        const long mod = 1000000007;
        foreach (var c in combination)
        {
            ans = (ans * c) % mod;
        }
        Console.WriteLine(ans);
    }
}


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.Linq;
      |       ^~~~~~
a.cc:3:7: error: expected nested-name-specifier before 'System'
    3 | using System.Collections.Generic;
      |       ^~~~~~
a.cc:8:15: error: expected ':' before 'List'
    8 |         public List<long> list;
      |               ^~~~~
      |               :
a.cc:8:16: error: 'List' does not name a type
    8 |         public List<long> list;
      |                ^~~~
a.cc:9:15: error: expected ':' before 'Connection'
    9 |         public Connection(int index)
      |               ^~~~~~~~~~~
      |               :
a.cc:13:6: error: expected ';' after struct definition
   13 |     }
      |      ^
      |      ;
a.cc:57:2: error: expected ';' after class definition
   57 | }
      |  ^
      |  ;
a.cc: In constructor 'Program::Connection::Connection(int)':
a.cc:11:13: error: 'list' was not declared in this scope
   11 |             list = new List<long>();
      |             ^~~~
a.cc:11:24: error: 'List' does not name a type
   11 |             list = new List<long>();
      |                        ^~~~
a.cc:11:29: error: expected primary-expression before 'long'
   11 |             list = new List<long>();
      |                             ^~~~
a.cc: In static member function 'static void Program::Main()':
a.cc:17:9: error: 'var' was not declared in this scope
   17 |         var nk = Console.ReadLine().Split(' ').Select(x => Int64.Parse(x)).ToArray();
      |         ^~~
a.cc:18:13: error: expected ';' before 'N'
   18 |         var N = nk[0];
      |             ^
a.cc:19:13: error: expected ';' before 'K'
   19 |         var K = nk[1];
      |             ^
a.cc:21:13: error: expected ';' before 'connection'
   21 |         var connection = new Connection[N];
      |             ^~~~~~~~~~
a.cc:22:29: error: 'N' was not declared in this scope
   22 |         for (int i = 0; i < N; ++i) connection[i] = new Connection(i);
      |                             ^
a.cc:22:37: error: 'connection' was not declared in this scope; did you mean 'Connection'?
   22 |         for (int i = 0; i < N; ++i) connection[i] = new Connection(i);
      |                                     ^~~~~~~~~~
      |                                     Connection
a.cc:23:24: error: 'N' was not declared in this scope
   23 |         for (int i=0;i<N-1;++i)
      |                        ^
a.cc:25:17: error: expected ';' before 'ab'
   25 |             var ab = Console.ReadLine().Split(' ').Select(x => Int64.Parse(x)).ToArray();
      |                 ^~
a.cc:26:13: error: 'connection' was not declared in this scope; did you mean 'Connection'?
   26 |             connection[ab[0] - 1].list.Add(ab[1]-1);
      |             ^~~~~~~~~~
      |             Connection
a.cc:26:24: error: 'ab' was not declared in this scope
   26 |             connection[ab[0] - 1].list.Add(ab[1]-1);
      |                        ^~
a.cc:30:13: error: expected ';' before 'combination'
   30 |         var combination = new long[N];
      |             ^~~~~~~~~~~
a.cc:31:9: error: 'combination' was not declared in this scope
   31 |         combination[0] = K;
      |         ^~~~~~~~~~~
a.cc:31:26: error: 'K' was not declared in this scope
   31 |         combination[0] = K;
      |                          ^
a.cc:32:13: error: expected ';' before 'queue'
   32 |         var queue = new Queue<long[]>();
      |             ^~~~~
a.cc:33:9: error: 'queue' was not declared in this scope
   33 |         queue.Enqueue(new long[2] { -1, 0 });
      |         ^~~~~
a.cc:36:17: error: expected ';' before 'current'
   36 |             var current = queue.Dequeue();
      |                 ^~~~~~~
a.cc:37:17: error: expected ';' before 'parent'
   37 |             var parent = current[0];
      |                 ^~~~~~
a.cc:38:17: error: expected ';' before 'node'
   38 |             var node = current[1];
      |                 ^~~~
a.cc:39:17: error: expected ';' before 'k'
   39 |             var k = parent < 0 ? K - 1 : K - 2;
      |                 ^
a.cc:40:26: error: expected ')' before 'l'
   40 |             foreach (var l in connection[node].list)
      |                          ^
a.cc:40:21: note: to match this '('
   40 |             foreach (var l in connection[node].list)
      |                     ^
a.cc:40:13: error: 'foreach' was not declared in this scope
   40 |             foreach (var l in connection[node].list)
      |             ^~~~~~~
a.cc:49:13: error: expected ';' before 'ans'
   49 |         var ans = 1L;
      |             ^~~
a.cc:51:22: error: expected ')' before 'c'
   51 |         foreach (var c in combination)
      |                      ^
a.cc:51:17: note: to match this '('
   51 |         foreach (var c in combination)
      |                 ^
a.cc:51:9: error: 'foreach' was not declared in this scope
   51 |         foreach (var c in combination)
      |         ^~~~~~~
a.cc:55:9: error: 'Console' was not declared in this scope
   55 |         Console.WriteLine(ans);
      |         ^~~~~~~
a.cc:55:27: error: 'ans' was not declared in this scope
   55 |         Console.WriteLine(ans);
      |                           ^~~