def Fib(n):
  F=[[1,1],
     [1,0]]
  if (n==0):
    return
  power(F,n-1)
  return F[0][0]

def multiply(F,M):

  w = (F[0][0] * M[0][0])+(F[0][1] * M[1][0])
  x = (F[0][0] * M[0][1])+(F[0][1] * M[1][1])
  y = (F[1][0] * M[0][0])+(F[1][1] * M[1][0])
  z = (F[1][0] * M[0][1])+(F[1][0] * M[1][1])

  F[0][0] = w
  F[0][1] = x
  F[1][0] = y
  F[1][1] = z

def power(F,n):
  M = [[1,1],
       [1,0]]
  for i in range(2,n+1):
    multiply(F,M)

#print(Fib(2))
for i in range(10000):
  if(Fib(i) > 4000000 ):
    k = i
    print(i)
    print(Fib(i))
    break

EvenSum = 0
last_numb = i
for i in range(2,last_numb,3):
  if(Fib(i)<4000000):
    EvenSum = EvenSum + Fib(i)
  elif(Fib(i)>4000000):
    break

print(EvenSum)