gc: option -- unrecognized
Usage: gc [-necCaDUrsv?] <files>
  -n - print number of nodes
  -e - print number of edges
  -c - print number of connected components
  -C - print number of clusters
  -a - print all counts
  -D - only directed graphs
  -U - only undirected graphs
  -r - recursively analyze subgraphs
  -s - silent
  -v - verbose
  -? - print usage
By default, gc prints nodes and edges
If no files are specified, stdin is used