v = int(input("Please enter N: "))

sum = 0
f1 = 1
f2 = 2
while f2 < v:
    if f2 % 2 == 0 :
        sum = sum + f2
    f1,f2 = f2, f1+f2
    #tmp = f2
    #f2 = f1 + f2
    #f1 = tmp

print("The sum of the even-valued Fibonacci numbers less than ", v, " is ", sum)