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#!/usr/bin/perl
use strict;
use warnings;
use feature 'say';
my $input = shift @ARGV;
chomp $input;
die "Invalid input, enter numbers greater than 1.\n" if $input <= 1;
say $input and exit 0 if is_prime($input) == 1;
if ($input % 2 == 0) {
foreach my $i (2 ... $input / 2) {
my $diff = $input - $i;
say "$i + $diff"
if is_prime($i) and is_prime($diff);
}
} elsif (is_prime($input - 2)) {
say "2 + $input";
} else {
foreach my $i (2 ... ($input - 3) / 2) {
my $diff = $input - 3 - $i;
say "3 + $i + $diff"
if is_prime($i) and is_prime($diff);
}
}
sub is_prime {
my $num = shift @_;
foreach my $i (2 ... sqrt($num)) {
return 0 if $num % $i == 0;
}
return 1;
}
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