 The arrow is called the "inverted arrow" of .The adjacency matrix of a multidigraph with loops is the integer-valued matrix with rows and columns corresponding to the vertices, where a nondiagonal entry "a""ij" is the number of arrows from vertex "i" to vertex "j", and the diagonal entry "a""ii" is the number of loops at vertex "i".The adjacency matrix of a directed graph is unique up to identical permutation of rows and columns.