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

my %hash;

while (my $line = <DATA>) {
    chomp $line;
    next if $line =~ /dG\s=\s(.*?)\s/;

    my ($sNum, $nt, undef, $connect) = split(/\s+/, $line);
    $hash{$nt} = $connect;
}

foreach my $key (keys %hash) {
    print "$key\t$hash{$key}\n";
}

__DATA__
300	 dG = -62.54   [initially -70.70] gi178893_M23263_rna_300-1 
4	U	3	5	0	4
5	U	4	6	0	5
14	G	13	15	30	14
15	A	14	16	29	15
16	G	15	17	28	16
18	A	17	19	26	18
19	C	18	20	25	19

##</code><code>##

A	19
C	20
G	17
U	6