s = gets.to_i
lc = Array.new(s - 3 + 1, 0)
ln = Array.new(s - 3 + 1, 0)
lc[0] = 1

d = 10 ** 9 + 7

a = 1
b = s - 3 * a
sum = 0
while b >= 0 do
  stmp = 0
  (0..b).each do |i|
    stmp = (stmp + lc[i]) % d
    ln[i] = stmp
  end
  sum = (sum + ln[b]) % d
  a += 1
  b = s - 3 * a
  lc, ln = ln, lc
end

puts sum
