class Vec2(object):
  def __init__(self, x, y):
    self.x = x
    self.y = y

def dot(v, w):
  return v.x * w.x + v.y * w.y

class Mat22(object):
  def __init__(self, a, b, c, d):
    self.a = a
    self.b = b
    self.c = c
    self.d = d
  
  def rows(self):
    yield Vec2(self.a, self.b)
    yield Vec2(self.c, self.d)
  
  def cols(self):
    yield Vec2(self.a, self.c)
    yield Vec2(self.b, self.d)
  
  def __mul__(m, n):
    return Mat22(*(
      dot(v, w)
      for w in n.rows()
      for v in m.cols()
    ))

def pow(x, p):
  if p == 1:
    return x
  z = pow(x, p // 2)
  y = z * z
  if p % 2 == 1:
    y *= x
  return y

def fib(n):
  return pow(Mat22(1, 1, 1, 0), n).b

if __name__ == '__main__':
  import sys 
  print fib(int(sys.argv[1]))