class Stack {

//Initializing stack with an empty array

constructor() {

this.arr = [];

var top = 0;

}

//push_back is used to push the elements in the stack

push_back(num) {

arr[top] = num;

top++;

}

//peek is used to return the element which is on the top of stack

peek() {

return arr[top];

}

//pop returns the element which is at the top and also removes it from the stack

pop() {

if (this.isEmpty()) {

console.log("UnderFlow");

return 0;

} else {

var temp = arr[top];

top--;

console.log("One element has been removed from the stack");

return temp;

}

}

//isEmpty is used to check whether the stack is empty or not

isEmpty() {

if (top == 0) {

return true;

} else {

return false;

}

}

// print is used to print all the elements of the stack

print() {

var output = "";

for (var i = 0; i < top; i++) {

output += arr[i] + " ";

}

return output;

}

//size is used to return the size of the stack

count() {

return top;

}

}

//Implementation

//Taking input from the user that how many values he/she wants to push into the stack

var input = prompt(

"Enter the number of values you want to push into the stack"

);

var another_arr = []; //Declaring the array

input = parseInt(input);

for (var i = 0; i < input; i++) {

//Taking array values as an input from the user

another_arr[i] = prompt("Enter Element " + (i + 1));

}

/*I will be taking the value of input be 3 and array values as 56,75,24 for explanation. */

var input = 3;

const another_arr = [56, 75, 24];

//Making an object of the stack class

var mystack = new Stack();

//Checking whether the stack is empty or not by isEmpty()

if (mystack.isEmpty() == true) {

console.log("The stack is empty right now");

} else {

console.log("The stack has elements in it");

}

//We can check it by count() also but it will not return true or false

console.log("The size of the current stack is", mystack.count()); //It will print 0.

//Pushing elements in the stack

for (var i = 0; i < input; i++) {

mystack.push_back(another_arr[i]);

}

//After pushing all the elements then mystack will be [56,75,24]

//Printing the new size of the array using count()

console.log("The new size of stack is ", count()); // It will print 3.

//Printing the stack with print()

console.log("The elements present in stack are ", mystack.print()); //It will print 56 75 24.

//Removing the topmost element from the stack by pop()

var removed_element = mystack.pop(); //This will return 24.

console.log("The element which is popped from the stack is ", removed_element); //It will print 24

//Printing the stack after removing the element using print()

console.log(

"The elements present after removing one element in stack are ",

mystack.print()

); //It will print 56 75