#!/usr/bin/perl
use v5.14;
use strict;
use warnings;

my $result = 0;


sub fib
{
 my @frame = @_;

 $frame[0] += $frame[1];
 $frame[1] = $frame[2];
 $frame[2] = $frame[3];
 
 count($frame[0]);

 return fib(@frame) unless($frame[0] >= 4_000_000);
} 

sub count
{
        my $increment = shift;
        if(($increment  % 2) == 0)
        {
                $result += $increment;
        }
}

fib(1,2,3);
say $result;