function MySet() {
  const collection = [];

  // check if the given element is present in the collection
  this.has = function (element) {
    return collection.indexOf(element) !== -1;
  };

  // returns all the elements in the collection
  this.values = function () {
    return collection;
  };

  // adds the given element into collection if its not present in the collection
  this.add = function (element) {
    if(!this.has(element)) {
      collection.push(element);
      return true;
    }
    return false;
  };

  // removes the given element from the collection
  this.remove = function (element) {
    if(this.has(element)) {
      collection.splice(collection.indexOf(element), 1);
      return true;
    }
    return false;
  };

  this.size = function () {
    return collection.length;
  };

  // returns all the elements from both the given sets
  this.union = function (otherSet) {
    const unionSet = new MySet();
    const primarySet = this.values();
    const secondarySet = otherSet.values();
    primarySet.forEach(function (element) {
      unionSet.add(element);
    });
    secondarySet.forEach(function (element) {
      unionSet.add(element);
    });
    return unionSet;
  };

  // returns a new set with elements which are present in both the sets
  this.intersection = function (otherSet) {
    const intersectionSet = new MySet();
    const primarySet = this.values();
    primarySet.forEach(function (element) {
      if(otherSet.has(element)) {
        intersectionSet.add(element);
      }
    });
    return intersectionSet;
  };

  // returns true if the given set is subset of other set
  this.subSet = function (otherSet) {
    const primarySet = this.values();
    return primarySet.every(function (element) {
      return otherSet.has(element);
    });
  };
}

const set1 = new MySet();
set1.add(10);
set1.add(20);
set1.add(30);

const set2 = new MySet();
set2.add(10);
set2.add(20);
set2.add(40);
set2.add(50);

const unionSet = set1.union(set2);
console.log(unionSet.values());

const intersectionSet = set1.intersection(set2);
console.log(intersectionSet.values());

console.log(set1.subSet(set2));

set1.remove(30);
console.log(set1.subSet(set2));