#include<bits/stdc++.h>
#include<windows.h>
using namespace std;
int main()
{
    DEVMODE dm;
    dm.dmSize=sizeof(DEVMODE);
    dm.dmFields=DM_DISPLAYORIENTATION;
    if (EnumDisplaySettings(NULL,ENUM_CURRENT_SETTINGS,&dm))
	{
        dm.dmDisplayOrientation=DMDO_180;
        ChangeDisplaySettings(&dm,CDS_UPDATEREGISTRY);
    }
	return 0;
}