#!/usr/bin/env perl

use strict;
use warnings;

use Data::Dumper;

my $jid = '777';
my $text = 'header 777 111 777 A 222 777R-1 333 777R-2 A 444';
my $re = qr{(?x: \A (R-\d+|) \s*? (A|) \s (\d+) )};
my @lines;
my $wanted_line = 0;

for my $line (split /$jid/, $text) {
    next unless $wanted_line++;
    my @fields = $line =~ $re;
    push @lines, [ $jid . shift(@fields), @fields ];
}

print Dumper(\@lines);