pool	subject
A	0
A	2
A	3
A	7
B	4
B	5
B	6
B	1
C	0
C	3
C	4
C	1
D	5
D	6
D	7
D	2
E	0
E	4
E	5
E	2
F	6
F	7
F	1
F	3