limit = 4000000
sum = 0
nextFibonacci = 1
currentFibonacci = 1
previousFibonacci = 0

while currentFibonacci < limit:
    if currentFibonacci % 2 == 0:
        sum += currentFibonacci
    nextFibonacci = currentFibonacci + previousFibonacci
    previousFibonacci = currentFibonacci
    currentFibonacci = nextFibonacci

print("The sum of all even-valued Fibonacci terms below four million is: %d" % (sum))