text: """
  Problem:
  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
  n, find the sum of the even-valued terms. e.g. for n=10, we have {2,8}, sum is
  10.
  """
  def solution(n):
      """Returns the sum of all fibonacci sequence even elements that are lower
      or equals to n.
  
      >>> solution(10)
      10
      >>> solution(15)
      10
      >>> solution(2)
      2
      >>> solution(1)
      0
      >>> solution(34)
      44
      """
      i = 1
      j = 2
      sum = 0
      while j <= n:
          if j % 2 == 0:
              sum += j
          i, j = j, i + j
  
      return sum
  
  
  if __name__ == "__main__":
      print(solution(int(input().strip())))
  