The input graph is a hydrogen-count labelled graph (HLG) where each atom is encoded in a vector with the following properties: element number, period, group, number of electrons on the last subshell + atom's charge, number of last shells, the total number of hydrogens, whether or not the atom is in a ring, number of neighbours and counts of single, double, triple and aromatic bonds near current atom. Each property is normalised with a natural logarithm for numerical stability. As a result, the input for the encoder consists of atom feature vectors with dimension 12 and the graph's adjacency matrix.