INPUT_FILE1.TXT
#REACTANT    #REACTION NO.
A                 1
E                 1
C                 1
A                 2
B                 2

##</code><code>##

INPUT_FILE2.TXT
#PRODUCT       #REACTION NO.
F                  1
H                  1
L                  1
G                  2
I                  2

##</code><code>##

reactant: E, product: F
reactant: E, product: H
reactant: E, product: L
reactant: C, product: F
reactant: C, product: H
reactant: C, product: L
reactant: A, product: F
reactant: A, product: H
reactant: A, product: L
reactant: A, product: G
reactant: A, product: I
reactant: B, product: G
reactant: B, product: I