基本的c++代码问题

我需要一些C++代码方面的帮助。我正在尝试制作一个程序，让单词向上和向下在屏幕上显示。我想让它这样做三次。我的程序是成功的，单词做了我想让他们做的事。然而，它没有做三次。我把它放在for循环中，所以我不确定出了什么问题。我在学习，所以我只需要帮助来理解我做错了什么。这是我的代码：

#include <iostream>
#include<windows.h> 
using namespace std; 
int main() 
{ 
    HANDLE screen = GetStdHandle(STD_OUTPUT_HANDLE); 
    COORD posUp = {5,25}; 
    COORD posDown = {68,1}; 
    SetConsoleCursorPosition(screen, posUp); 
    cout<<"Up"<<endl; 
    SetConsoleCursorPosition(screen, posDown); 
    cout<< "Down"<<endl; 
    Sleep(400); 
    for(int comeback=1; comeback<=3; comeback++) { 
        while(posUp.Y > 1 && posDown.Y < 24) { 
            SetConsoleCursorPosition(screen,posUp); 
            cout<<" "<<endl; 
            posUp.Y--; 
            SetConsoleCursorPosition(screen, posUp); 
            cout<<"Up"<<endl; 
            SetConsoleCursorPosition(screen, posDown); 
            cout<<" "; 
            posDown.Y++; 
            SetConsoleCursorPosition(screen, posDown); 
            cout<<"Down"<<endl; 
            Sleep(100); 
        } 
        SetConsoleCursorPosition(screen, posUp); 
        cout<<" "<<endl; 
        SetConsoleCursorPosition(screen, posDown); 
        cout<< " "<<endl; 
        Sleep(100); 
    } 
    return 0; 
}