N = gets.to_i

if N == 1
  puts 2
  exit
end

def k_fib(k)
  nums = [0] * (k - 1)
  nums << 1
  sum = 1

  while nums.last < N
    l = nums.size
    nums << sum
    sum -= nums[l - k]
    sum += nums.last

    if nums.last == N
      return true
    end
  end

  false
end

k = 2

while 2 ** (k - 1) <= N
  if k_fib(k)
    puts k
    exit
  end

  k += 1
end

puts -1