求大神帮忙看一下c++代码哪里错了，谢谢。

#include<bits/stdc++.h>

#include<Windows.h>

#include<tlhelp32.h>

#include<shlwapi.h>

#include<psapi.h>

#include<commctrl.h>

using namespace std;

int main()

{

    HDC a;

    int x=0,y=0;

    a=GetDC(GetDesktopWindow());

    while(true){

        //if(y>=GetSystemMetrics(SM_CYSCREEN)){

        //  x=0;

        //  y=0;

        //}

    StretchBlt(a,x+25,y+25,

    GetSystemMetrics(SM_CXSCREEN)-(x+25)*2,

    GetSystemMetrics(SM_CYSCREEN)-(y+25)*2,

    a, 0, 0,GetSystemMetrics(SM_CXSCREEN),

    GetSystemMetrics(SM_CYSCREEN),13369376);

    Sleep(1000);

    }

    return 0;

 }