'''
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.
'''

n1 = 1
n2 = 2

totalEven = 0

while n2 <= 4000000:

    total = n1+n2

    if total%2 == 0: totalEven += total

    n1 = n2
    n2 = total

print(totalEven)
