Language: C++

using System;
using System.Collections.Generic;

namespace TriangleRight
{
	class MainClass
	{
		public static void Main(string[] args) 
		{
			string str; 
			List<string> status = new List<string> ();
			while (!string.IsNullOrEmpty(str = Console.ReadLine())) {
				string[] input = str.Split(' ');
				int a, b, c;
				if (input.Length > 2 && input.Length <= 3) {
					a = input [0].Equals ("") ? 0 : int.Parse (input [0]);
					b = input [1].Equals ("") ? 0 : int.Parse (input [1]);
					c = input [2].Equals ("") ? 0 : int.Parse (input [2]);
				} else {
					a = input [0].Equals ("") ? 0 : int.Parse (input [0]);
					b = 0;
					c = 0;
				}

				if (a + b > c) {
					if (a + c > b) {
						if (b + c > a) {
							status.Add ("YES");
						} else {
							status.Add ("NO");
						}
					} else {
						status.Add ("NO");
					}
				} else {
					status.Add ("NO");
				}
			};

			for (int i = 0; i < status.Count; i++) {
				Console.WriteLine (status[i]);
			}


			Console.Read ();
		}
	}
}

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:8:23: error: expected ':' before 'static'
    8 |                 public static void Main(string[] args)
      |                       ^~~~~~~
      |                       :
a.cc:8:41: error: 'string' has not been declared
    8 |                 public static void Main(string[] args)
      |                                         ^~~~~~
a.cc:8:50: error: expected ',' or '...' before 'args'
    8 |                 public static void Main(string[] args)
      |                                                  ^~~~
a.cc:47:10: error: expected ';' after class definition
   47 |         }
      |          ^
      |          ;
a.cc: In static member function 'static void TriangleRight::MainClass::Main(int*)':
a.cc:10:25: error: 'string' was not declared in this scope
   10 |                         string str;
      |                         ^~~~~~
a.cc:11:25: error: 'List' was not declared in this scope
   11 |                         List<string> status = new List<string> ();
      |                         ^~~~
a.cc:11:38: error: 'status' was not declared in this scope; did you mean 'static'?
   11 |                         List<string> status = new List<string> ();
      |                                      ^~~~~~
      |                                      static
a.cc:11:51: error: 'List' does not name a type
   11 |                         List<string> status = new List<string> ();
      |                                                   ^~~~
a.cc:11:65: error: expected primary-expression before ')' token
   11 |                         List<string> status = new List<string> ();
      |                                                                 ^
a.cc:12:54: error: 'str' was not declared in this scope; did you mean 'std'?
   12 |                         while (!string.IsNullOrEmpty(str = Console.ReadLine())) {
      |                                                      ^~~
      |                                                      std
a.cc:12:60: error: 'Console' was not declared in this scope
   12 |                         while (!string.IsNullOrEmpty(str = Console.ReadLine())) {
      |                                                            ^~~~~~~
a.cc:13:40: error: expected primary-expression before ']' token
   13 |                                 string[] input = str.Split(' ');
      |                                        ^
a.cc:15:37: error: 'input' was not declared in this scope; did you mean 'int'?
   15 |                                 if (input.Length > 2 && input.Length <= 3) {
      |                                     ^~~~~
      |                                     int
a.cc:16:73: error: expected primary-expression before 'int'
   16 |                                         a = input [0].Equals ("") ? 0 : int.Parse (input [0]);
      |                                                                         ^~~
a.cc:17:73: error: expected primary-expression before 'int'
   17 |                                         b = input [1].Equals ("") ? 0 : int.Parse (input [1]);
      |                                                                         ^~~
a.cc:18:73: error: expected primary-expression before 'int'
   18 |                                         c = input [2].Equals ("") ? 0 : int.Parse (input [2]);
      |                                                                         ^~~
a.cc:20:73: error: expected primary-expression before 'int'
   20 |                                         a = input [0].Equals ("") ? 0 : int.Parse (input [0]);
      |                                                                         ^~~
a.cc:41:33: error: 'Console' was not declared in this scope
   41 |                                 Console.WriteLine (status[i]);
      |                                 ^~~~~~~
a.cc:45:25: error: 'Console' was not declared in this scope
   45 |                         Console.Read ();
      |                         ^~~~~~~