#! /local/bin/perl
use strict;
use warnings;

my %degree;

my $filename = "edges.txt";
open(my $fh, "<", $filename) or die "Can't open '$filename': $!";
while (<$fh>) {
  if (/(\S+)\t(\S+)/) {
    $degree{$1}++;
    $degree{$2}++;
  }
}

my %degree_distribution;
$degree_distribution{$_}++ for values %degree;

for my $id (sort keys %degree) {
  my $d = $degree{$id};
  my $freq = $degree_distribution{$d};
  print "$id has degree:\t$d\t(freq: $freq)\n";
}