#include <GL/gl.h>
#include <GL/glut.h>
int r, p, i,decision,x, y, Dx, Dy;



void display(void)
{

    x=0, y=r;
    decision= (5/4)-r;


    while (y > x)
    {
        glColor3f(1.0,1.0,0.0);
        glBegin(GL_POINTS);
        if (decision < 0)
        {
            x++;
            decision += 2*x+1;
        }
        else
        {
            y--;
            x++;
            decision += 2*(x-y)+1;
        }

        glVertex2d(x, y);
        glVertex2d(x, -y);
        glVertex2d(-x, y);
        glVertex2d(-x, -y);
        glVertex2d(y, x);
        glVertex2d(-y, x);
        glVertex2d(y, -x);
        glVertex2d(-y, -x);

    }
    glEnd();
    glFlush();
}




void init (void)
{

    glClearColor (0.0, 0.0, 0.0, 0.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(-500, 500, -500, 600);
}

int main(int argc, char** argv)
{

    printf("Enter redius \n");
    scanf("%d", &r);
    glutInit(&argc, argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize (500, 500);
    glutInitWindowPosition (100, 100);
    glutCreateWindow ("Sumon's Circle Drawing");
    init ();
    glutDisplayFunc(display);
    glutMainLoop();
    return 0; /* ISO C requires main to return int. */
}