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

my @arr = <DATA>;
chomp @arr;

local $,="\n";

while(@arr) {

    my @str = shift @arr;

    my @reslt;
    push(@reslt,$str[0]);

    while (@str) {
        my $str = shift @str;

        my (undef, $s1, undef, $s2, $flag) = split(/[ \.]/,$str);

        my $count = 0;
        my $acount = 0; #to arrange o/p

        while($count < @arr) {
            my $strtocheck = $arr[$count];

            if($strtocheck =~ /$s1|$s2/) {
                $acount++;
                if($acount == 2 || ($flag && $flag == 1)) {
                    unshift(@reslt,$strtocheck);
                    unshift(@str,$strtocheck." 1");
                }
                else {
                    push(@reslt,$strtocheck);
                    push(@str,$strtocheck);
                }
                splice(@arr,$count,1);
            } else {
                $count++;
            }
        }
    }
    print @reslt,"\n";
}

__DATA__
ID5141.C1665 ID5141.C2448
ID5141.C1253 ID5144.C2039
ID5141.C1596 ID5144.C1956
ID5141.C1906 ID5144.C2149
ID5141.C1221 ID5144.C1956
ID5141.C2149 ID5141.C2386
ID5141.C2039 ID5142.C1221
ID5141.C5887 ID5141.C7685
ID5141.C1005 ID5142.C2808
ID5141.C1046 ID5141.C1596
ID5141.C2386 ID5141.C4990
ID5141.C7685 ID5141.C4888