#!/usr/bin/perl

# Calculate the time difference between every download of a paper
# and every citation on a paper
# Author: Ian Hickman

use strict;

my (%table, @cits, @hits);

while( <STDIN> ){
  @cits=split;
  $_=<STDIN>;
  @hits=split;
  for( my $c=2; $c<@cits; $c++ ){
    for( my $h=3; $h<@hits; $h++ ){
      my $r=($hits[$h]-$cits[$c]);
      $table{$r}++;
    }
  }
}

my $time;

foreach $time ( keys ( %table )){
  print"$time $table{$time}\n";
}