# From Project Euler: https://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.

total_value = 2
lower = 1
upper = 2

while lower + upper < 4000000:
    current = lower + upper

    if current % 2 == 0:
        total_value += current

    lower = upper
    upper = current

print total_value

