M = 10**9+7

$dp = {}
def f(n, i)
  $dp[[n,i]] ||= if n == 0
    1
  elsif n < 0
    0
  else
    [1,2,3].map{|j|
      j == i ? 0 : f(n - j, j)
    }.sum % M
  end
end

N = gets.to_i
p [1,2,3].map{|i| f(N-i, i) }.sum % M