Stack as a queue, C#

Language: Layout:

//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Stack<int> stack1 = new Stack<int>();
            Stack<int> stack2 = new Stack<int>();
            
            push(stack1, 6);
            push(stack1, 5);
            push(stack1, 4);
            top(stack1);
            foreach(int i in stack1)
            {
                Console.WriteLine(i);
            }
            
            stack2.Push(pop(stack1));
            stack2.Push(pop(stack1));
            stack2.Push(pop(stack1));
            foreach(int i in stack2)
            {
                Console.WriteLine(i);
            }
        }
        
        public static void push(Stack<int> stk1, int num)
        {
            stk1.Push(num);
            
        }
        
        public static int pop(Stack<int> stk1)
        {
            if(stk1 != null)
                return(stk1.Pop());  
            return 0;
        }
        
        public static void top(Stack<int> stk1)
        {
            if(stk1 != null)
                stk1.Peek();
            
        }
        
        
        
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,16 sec, absolute running time: 0,09 sec, cpu time: 0,08 sec, average memory usage: 12 Mb, average nr of threads: 2