=begin

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, ...

Find the sum of all the even-valued terms in the sequence which do not exceed one million.

=end

fl = 1
f = 2
which = 0
sum = 0
while f < 1000000
  sum += f if ((which % 3) == 0)
  which += 1
  newf = f + fl
  fl = f
  f = newf
end

print sum