ss (it doesn't matter which process it is),
otherwise you will end up with multiple edges. For example, in the
following program we read edges from the standard input of process 0,
adding those edges by name. Vertices and edges will be created and
distributed automatically.</p>
<blockquote>
<pre class="literal-block">
Graph g;
if (process_id(g.process_group()) == 0) {
  // Only process 0 loads the graph, which is distributed automatically
  std:string source, target;
  for(std::cin &gt;&gt; source &gt;&gt; 