using System;
using System.Collections.Generic;
using System.Threading;
 
static class Program
{
	private static Queue<int> q = new Queue<int>();
 
	static void Main(string[] args)
	{
		Thread[] thrds = new Thread[100];
		for (int i = 0; i < 100; i++)
		{
			thrds[i] = new Thread(do_safe);
			//thrds[i] = new Thread(do_unsafe); // <--
			thrds[i].Start(i);
		}
 
		for (int i = 0; i < 100; i++)
		{
			thrds[i].Join();
		}
 
		foreach (int i in q)
		{
			Console.WriteLine(i);
		}
	}
	private static void do_safe(object k)
	{
		int val = (int)k;
		for (int i = 0; i < 100; i++) // do something
		{
			val += i;
			Thread.Sleep(1);
		}
 
		lock (q)
			q.Enqueue(val); // with locking
	}
	private static void do_unsafe(object k)
	{
		int val = (int)k;
		for (int i = 0; i < 100; i++) // do something
		{
			val += i;
			Thread.Sleep(1);
		}
 
		q.Enqueue(val); // without locking
	}
}
 

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