'''
Problem:
Each new term in the Fibonacci sequence is generated by adding the previous two terms. 
                0,1,1,2,3,5,8,13,21,34,55,89,..
Every third term from 0 is even So using this I have written a simple code
By considering the terms in the Fibonacci sequence whose values do not exceed n, find the sum of the even-valued terms.
e.g. for n=10, we have {2,8}, sum is 10.
'''
"""Python 3"""
n = int(input())
a=0
b=2
count=0
while 4*b+a<n:
    c=4*b+a
    a=b
    b=c
    count=count+a
print(count+b)