rec	rng	-rng	rng-	-rng-	--rng-	--rng	rng+	-rng+	--rng+	Y1Y2
X1	t		t				t			
a	t	t	t	t			t	t		
b	t	t	t	t			t	t		
X1	t	t	t	t			t	t		
c	t	t	t	t			t	t		
X2	t	t	t	t			t	t		
1	t	t	t	t	t	t	t	t	t	
2	t	t	t	t	t	t	t	t	t	
3	t	t	t	t	t	t	t	t	t	
Y1	t	t				t	end	t	t	t
r							end	end	t	t
s							end	end	t	t
Y2							end	end	t	t
t										
Y2										
X1X2	t		t				t			
Y1Y2	t	t				t	end	t	t	t
X1X2	t		t				t			
Y1	t	t				t	end	t	t	t
a							end	end	t	t
Y2							end	end	t	t
X1	t		t				t			
b	t	t	t	t			t	t		
X2	t	t	t	t			t	t