#include <graphics.h>
#define R 100
int main()
{
    int dx=1,y=0,x=300,dy=1,x1=0,y1=400,dx1=1,dy1=1;
    initgraph(800,600);
    setbkcolor(BLACK);
    setlinewidth(5);
   
    for(;is_run();delay_fps(200))
    {  
        if(y>=getheight()-2*R)
        {
            setcolor(RED);
            dy=-1;
        }
        if(y<=0)
        {
            setcolor(BLUE);
            dy=1;
        }
        if(x>=getwidth()-2*R)
        {
            setcolor(GREEN);
            dx=-1;
        }
        if(x<=0)
        {
            setcolor(YELLOW);
            dx=1;
        }
        if(y1>=getheight()-2*R)
        {
            setcolor(RED);
            dy1=-1;
        }
        if(y1<=0)
        {
            setcolor(BLUE);
            dy1=1;
        }
        if(x1>=getwidth()-2*R)
        {
            setcolor(GREEN);
            dx1=-1;
        }
        if(x1<=0)
        {
            setcolor(YELLOW);
            dx1=1;
        }
        cleardevice();
        y=y+dy;
        x=x+dx;
        circle(x+R,y+R,R);
        y1=y1+dy1;
        x1=x1+dx1;
        circle(x1+R,y1+R,R);
    }
    getch();
    closegraph();
    return 0;
}