s = 25;
for k=1 upto 6:
  beginfig(k);
    path a, r[], p[];
    picture p;
  
    a = fullcircle scaled (s*2);

    r1 = (0,0)--(0,s);
    r2 = (0,0)--(s,0);
    r3 = (0,0)--(-s,0);
    r4 = (0,0)--(0,-s);

    p1 = buildcycle(a,r1,r2);
    fill p1 withcolor black;

    p3 = buildcycle(a,r3,r4);
    fill p3 withcolor black;

    draw (-s,0){up}..(s,0){down}..cycle;

    p = currentpicture rotated (k*30) shifted (s,s);
    currentpicture:=nullpicture;
    draw p;
  
    draw bbox currentpicture;
    
  endfig;
endfor;

end