Syntax: congest [-n N] [filename]
This command will compute and print a congestion value for each cell instance. The values are print in sorted order, highest congestion to lowest. By default, all instances are listed, if the -n option is given, only the highest N instances are listed (N being a positive integer). If a filename is given, output goes to that file, otherwise output goes to the standard output. This command is intended to identify highly congested parts of a layout, which may benefit from additional fill in a subsequent routing run.