Solution Review: min() Function Using a Stack

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace chapter_4
{
    class newStack
    {
        //We will use two stacks mainStack to hold origional values
        //and minStack to hold minimum values. Top of minStack will always
        //be the minimum value from mainStack
        Stack <int> mainStack;
        Stack<int> minStack;
        public newStack(int size)
        {
            mainStack = new Stack<int>(size);
            minStack = new Stack<int>(size);
        }
        //Removes and returns value from newStack
        //1. Pop element from minStack to make it sync with mainStack.
        //2. Pop element from mainStack and return that value.
        int pop()
        {
            minStack.Pop();
            return mainStack.Pop();
        }
        //Pushes values into newStack
        //1. Push value in mainStack and check value with the top value of minStack
        //2. If value is greater than top, then push top in minStack
        //else push value in minStack.
        void push(int value)
        {
            mainStack.Push(value);
            if ( (minStack.Count != 0) && (value > minStack.Peek()) )
            {
                minStack.Push(minStack.Peek());
            }
            else
                minStack.Push(value);
        }
        //Returns minimum value from newStack in O(1) Time
        int min()
        {
            return minStack.Peek();
        }
        static void Main(string[] args)
        {
            newStack stack = new newStack(6);
            stack.push(5);
            stack.push(2);
            stack.push(4);
            stack.push(1);
            stack.push(3);
            stack.push(9);
            Console.WriteLine(stack.min());
            stack.pop();
            stack.pop();
            stack.pop();
            Console.WriteLine(stack.min());
            return ;
        }
    }
}