u=5mm;
t=5mm;
beginfig(1)
  w = 20u;
  h = 11t;

  fill (6u,u)--(7u,u)--(7u,4u)--(6u,4u)--cycle withcolor .8 white;
  fill (12u,u)--(13u,u)--(13u,4u)--(12u,4u)--cycle withcolor .8 white;
  fill (18u,u)--(19u,u)--(19u,4u)--(18u,4u)--cycle withcolor .8 white;
  label.bot(btex $A$ etex, (2.5u,u));
  label.bot(btex $B$ etex, (7.5u,u));
  label.bot(btex $C$ etex, (12.5u,u));
  label.bot(btex $D$ etex, (17.5u,u));


    
  for i = u step 5u until w:
  	draw (i,u)--(i+3u,u)--(i+3u,4u)--(i,4u)--cycle; 
	draw (i+u,u)--(i+u,4u);
	draw (i+2u,u)--(i+2u,4u);	
  endfor;

endfig;

beginfig(2)
  w := 20u;
  h := 11t;

  fill (u,u)--(2u,u)--(2u,4u)--(u,4u)--cycle withcolor .8 white;
  fill (3u,u)--(4u,u)--(4u,4u)--(3u,4u)--cycle withcolor .8 white;


  fill (6u,u)--(7u,u)--(7u,4u)--(6u,4u)--cycle withcolor .8 white;
  fill (7u,u)--(8u,u)--(8u,4u)--(7u,4u)--cycle withcolor .8 white;

  fill (12u,u)--(13u,u)--(13u,4u)--(12u,4u)--cycle withcolor .8 white;
  fill (13u,u)--(14u,u)--(14u,4u)--(13u,4u)--cycle withcolor .8 white;


  fill (16u,u)--(17u,u)--(17u,4u)--(16u,4u)--cycle withcolor .8 white;
  fill (17u,u)--(18u,u)--(18u,4u)--(17u,4u)--cycle withcolor .8 white;
  fill (18u,u)--(19u,u)--(19u,4u)--(18u,4u)--cycle withcolor .8 white;
 
  label.bot(btex $E$ etex, (2.5u,u));
  label.bot(btex $F$ etex, (7.5u,u));
  label.bot(btex $G$ etex, (12.5u,u));
  label.bot(btex $H$ etex, (17.5u,u));


    
  for i = u step 5u until w:
  	draw (i,u)--(i+3u,u)--(i+3u,4u)--(i,4u)--cycle; 
	draw (i+u,u)--(i+u,4u);
	draw (i+2u,u)--(i+2u,4u);	
  endfor;

endfig;



end.
                                 