output_description: Print -1 if it is impossible to lighten up Button 2. Otherwise, print the
  minimum number of times we need to press buttons in order to lighten up Button
  2.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      a_1
      a_2
      :
      a_N
attempt: import functools
  
  
  def inputs(num_of_input):
      ins = [input() for i in range(num_of_input)]
      return ins
  
  
  def solve(inputs):
      a = list(map(lambda x: int(x), inputs))
      a[1] = -1
      return wh(a, 2, 0)
  
  
  def wh(a, search, count):
      counts = []
  
      if search == 1:
          return count
  
      for i, value in enumerate(a):
          if value == search:
              counts.append(wh(a, i + 1, count + 1))
  
      counts_ignore_minus = list(filter(lambda x: x != -1, counts))
  
      if len(counts_ignore_minus) == 0:
          return -1
  
      min = counts_ignore_minus[0]
      for c in counts_ignore_minus:
          if min > c:
              min = c
      return min
  
problem_description: Statement
  
  Takahashi wants to gain muscle, and decides to work out at AtCoder Gym.
  
  The exercise machine at the gym has N buttons, and exactly one of the buttons
  is lighten up. These buttons are numbered 1 through N. When Button i is
  lighten up and you press it, the light is turned off, and then Button a_i will
  be lighten up. It is possible that i=a_i. When Button i is not lighten up,
  nothing will happen by pressing it.
  
  Initially, Button 1 is lighten up. Takahashi wants to quit pressing buttons
  when Button 2 is lighten up.
  
  Determine whether this is possible. If the answer is positive, find the
  minimum number of times he needs to press buttons.
samples: [{"input": "3\n    3\n    1\n    2", "output": "2\n    \n\nPress Button 1, then Button 3.\n\n* * *"}, {"input": "4\n    3\n    4\n    1\n    2", "output": "-1\n    \n\nPressing Button 1 lightens up Button 3, and vice versa, so Button 2 will never\nbe lighten up.\n\n* * *"}, {"input": "5\n    3\n    3\n    4\n    2\n    4", "output": "3"}]