[NTG-context] Venn diagram

All, I have: \startMPpage %figure library name: intersection %initialize scale numeric u; 10u=3in; %ellipses path A, B; A:=fullcircle xyscaled (4u,3u); B:=A shifted (2u,0); draw A withcolor red; label.ulft(btex $A$ etex, point 3 of A) withcolor red; draw B withcolor blue; label.urt(btex $B$ etex, point 1 of B) withcolor blue; %bounding box draw bbox currentpicture enlarged (0.5u,0.5u); \stopMPpage I need an easy way of shading these areas: 1. A intersect B 2. A union B 3. A intersect (complement of B) 4. (complement of A) intersect B Thanks