lim = 4000000 # 4 million
fst_term = 1
snd_term = 2
thd_term = 0
sum = 0

while ( snd_term < lim )

    if ( snd_term % 2 == 0)
        sum = sum + snd_term
    end

    thd_term = fst_term + snd_term
    fst_term = snd_term
    snd_term = thd_term
end

puts sum