A bipartite graph G = (S, T; E) is called

A bipartite graph G = (S, T; E) is called complete if every vertex in S is joined to every vertex in T by an edge, and is denoted by Kn1,n2, where n1 and n2 are the numbers of vertices in S and T, respectively. How many edges does this graph have?

PROBLEM SET 23.3: