func main()
	const mod: int :: 1000000007
	var n: int :: cui@inputInt()
	var dp: []int :: #[3]int
	do dp[2] :: 1
	for(1, n)
		var nx: []int :: #[3]int
		do nx[0] :: dp[2]
		do nx[1] :: dp[0]
		do nx[2] :: dp[0] + dp[1]
		for i(0, 2)
			do nx[i] :% mod
		end for
		var tmp: []int :: dp
		do dp :: nx
		do nx :: tmp
	end for
	var ans: int :: 0
	for i(0, 2)
		do ans :+ dp[i]
	end for
	do ans :% mod
	do cui@print("\{ans}\n")
end func