#!/usr/bin/perl -w
use strict;

my %hash = (a=>2, b=>1, c=>5, d=>3, e=>4);

my $input = "abcdaeec";

for (2, 3) {
    print "n=$_: ";
    my $n = $_ - 1;

    my @sums;
    while ( $input =~ /(.)(?=.{$n}(.))/g ) {
        push @sums, $hash{$1} + $hash{$2};
    }
    print "@sums\n";
}

__END__
n=2: 7 4 7 7 6 9
n=3: 5 3 9 7 7