https://hellohasan.com/2016/11/01/%e0%a6%95%e0%a6%bf%e0%a6%89-%e0%a6%a1%e0%a7%87%e0%a6%9f%e0%a6%be-%e0%a6%b8%e0%a7%8d%e0%a6%9f%e0%a7%8d%e0%a6%b0%e0%a6%be%e0%a6%95%e0%a6%9a%e0%a6%be%e0%a6%b0-queue-data-structure/