#include <graphics.h>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <conio.h>
#include <dos.h>

int gd,gm,x,y,n,h,x1,x2,x3,x4,y1,y2,y3,y4,xc,yc,l,i;
int xmax,ymax,raza,dx,dy;


void main(void)
{
	clrscr();
	//cleardevice();
	randomize();


	void *p;

	printf("Raza=");
	scanf("%d",&raza);

	detectgraph(&gd,&gm);
	initgraph(&gd,&gm,"C:\\borlandc\\bgi");
	cleardevice();

	xmax=getmaxx();
	ymax=getmaxy();
	xc=xmax/2;
	yc=ymax/2;
	x1=xc-raza-1;
	y1=yc-raza-1;
	x2=xc+raza+1;
	y2=yc+raza+1;
	line(0,0,0,ymax);
	line(0,ymax,xmax,ymax);
	line(xmax,ymax,xmax,0);
	line(xmax,0,0,0);
	circle(xc,yc,raza);
	p=malloc(imagesize(x1,y1,x2,y2));
	getimage(x1,y1,x2,y2,p);
	setcolor(BLACK);
	circle(xc,yc,raza);
	setcolor(WHITE);

	dx=1;
	dy=1;
	x=xc;
	y=yc;

	for(i=0;i<=1000;i++)
	{
		putimage(x,y,p,XOR_PUT);
		delay(1);
		putimage(x,y,p,XOR_PUT);
		x=x+dx;
		y=y+dy;
		if ((x==xmax-2*raza) || (x<=1) )
			dx=-dx;
		if ((y==ymax-2*raza) || (y<=1) )
			dy=-dy;
	}




	getch();
//  closegraph();

}