// Source code example for "A Practical Introduction
// to Data Structures and Algorithm Analysis"
// by Clifford A. Shaffer, Prentice Hall, 1998.
// Copyright 1998 by Clifford A. Shaffer

interface Edge {   // Interface for graph edges
  public int v1(); // Return the vertex it comes from
  public int v2(); // Return the vertex it goes to
} // interface Edge