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if (my_value && typeof my_value === 'object' && my_value.constructor === Array) {
         // my_value is an array!
}

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//add the given argument and throw exception object {name,message}
var add = function (a, b) {
    if (typeof a !== 'number' || typeof b !== 'number') {
             throw {
                 name: 'TypeError',
                 message: 'add needs numbers'
             }; 
    }
    return a + b; 
} 

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//sync v/s async

//Count # of lines
var fs = require('fs')

var fileName = process.argv[2]

//Async call
fs.readFile(fileName,function (err, data) {
    lst_ = data.toString();

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    //I/P    [1, 2, 4, ,6, 3, 7, 8]
    //O/P    5

    //NOTE : array is sorted
    //1 .total = n*(n+1)/2 leads to overflow if total can't be represented by the number O(n)
    //2. XOR (given array) ^ (numbers from 1-n) = missing number  O(n)
    //3. Binary search (Find out the hole wheather in first half/second half) (O log n)

    //Array: [1,2,3,4,5,6,8,9]

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    //If the given arrays is {1, 9, 8, 4, 0, 0, 2, 7, 0, 6, 0}
    //,it should be changed to {1, 9, 8, 4, 2, 7, 6, 0, 0, 0, 0}. 
    //The order of all other elements should be same. 
    //Expected time complexity is O(n) and extra space is O(1).

    public static void swap (int a[],int start,int end) {
        int tmp = a[start];
        a[start] = a[end];
        a[end] = tmp;
    }

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class Queue<T> {

    //Queue using DLL
    class Node {
        T data;
        Node prev;
        Node next;
        Node (T data) {
            this.data = data;
            this.next = null;

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    //Find Idx difference
    //Input: {34, 8, 10, 3, 2, 80, 30, 33, 1}
    //Output: 78

    //Input: {9, 2, 3, 4, 5, 6, 7, 8, 18, 0}
    //Output:16

    //Input:  {1, 2, 3, 4, 5, 6}
    //Output: 5

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  public static void reverse (int nums[],int start,int end) {
      while(start < end) {
          int tmp = nums[start];
          nums[start] = nums[end];
          nums[end] = tmp;
          start++;
          end--;
      }
  }

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//find RAGA journey

//US->Thila
//Thid->Bang
//India->Us

void topologicalSortUtil (string src,unordered_map<string,vector<string> >& travelG
        ,unordered_set<string>& visited,stack<string>& iStack) {

    visited.insert(src);

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//:pancake sorting
//:insert the spatuala to max item idx
//:flip the max item idx to first
//:flip all items to size - 1
//:reduce size

void flip  (int a[],int n) {
    int start = 0;
    int end = n;
    while (start < end) {