What is the output?

#include <iostream>
#include <queue>
#include<stack>
using namespace std;

int main()
{
    queue<int> q;    //declare an empty queue
    stack<int> s;    //declare an empty stack

    q.push(3);        //How push works?
    q.push(15);
    q.push(27);
    q.push(300);

    while(!q.empty())
    {
        cout<<q.front()<<" ";  //To see how a queue stores data
        q.pop();               //How pop works?
    }
    cout<<endl;

    int arr[]={2,4,6,8,10,12,14,16,18,20};

    for(int i=0; i<10; i++)    //Push elements of array to a queue
        q.push(arr[i]);

    while(!q.empty())
    {
        cout<<q.front()<<" ";
        q.pop();
    }
    cout<<endl;

    for(i=0; i<10; i++)        //Push elements of array to a stack
        s.push(arr[i]);

    while(!s.empty())
    {
        cout<<s.top()<<" ";
        s.pop();
    }
    cout<<endl;

    q.push(5);
    q.push(10);
    q.push(15);
    q.pop();
    q.push(20);

    while(!q.empty())
    {
        cout<<q.front()<<" ";
        q.pop();
    }
    cout<<endl;
    s.push(5);
    s.push(10);
    s.push(15);
    s.pop();
    s.push(20);

    while(!s.empty())
    {
        cout<<s.top()<<" ";
        s.pop();
    }
    cout<<endl;

    system("pause");
    return 0;
}