species_1 + species_2 -> species_3
2*species_5 -> species_4
species_4 -> 2*species_5
species_6 + species_8 -> species_7
species_3 + species_4 -> species_9
species_9 -> species_3 + species_4
species_7 + species_9 -> species_10
species_10 -> species_7 + species_9
species_10 -> species_11 + species_6
species_11 -> species_12 + species_4
species_18 + species_8 -> species_15
species_12 + species_13 -> species_14
species_14 -> species_12 + species_13
species_14 + species_15 -> species_16
species_16 -> species_14 + species_15
species_16 -> species_17 + species_18
species_17 -> species_13 + species_19
species_13 + species_19 -> species_17
species_15 + species_17 -> species_20
species_20 -> species_15 + species_17
species_20 -> species_18 + species_21
species_21 -> species_13 + species_22
species_12 -> species_23 + species_8
species_19 -> species_23 + 2*species_8
species_22 -> species_23 + 3*species_8