TIMTOWTDI

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11165687
use warnings;

my ($result, $x, $y) = (0, 0, 1);
($result, $x, $y) = ($result + ($y & 1 ? 0 : $y), $y, $x + $y) while $
+y <= 4e6;
print "result $result\n";
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Outputs:

result 4613732
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