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ProjectEuler02.pl

#http://projecteuler.net/problem=2

#Each new term in the Fibonacci sequence is generated by adding the previous two terms. 
#By starting with 1 and 2, the first 10 terms will be:
#1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
#By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.


use strict;
use warnings;

my $a = 0;
my $b = 1;
my $n = 0;

my $sum = 0;

while($n < 4000000)
{
    $n = $a + $b;
    if(($n % 2) == 0)
    {
        $sum += $n;        
    }
    $a = $b;
    $b = $n;
}
print $sum;