F = Array.new(80,1)
(2 ... F.size).each do |i|
  F[i] = F[i - 1] + F[i - 2]
end
A = 5.times.map{ gets.to_i }
ans = 5.downto(1).find do |n|
  i = 5 - n
  j = F.rindex(A[i])
  
  next false if j.nil?
  
  n.times.all? do |k|
    A[i + k] == F[j - k]
  end
end
puts ans || 0