N = int(raw_input())
ken = 1
kenken = 0
pa = 0

for i in range(1, N):
	newken = pa
	newkenken = ken
	newpa = ken + kenken
	ken = newken % 1000000007
	kenken = newkenken % 1000000007
	pa = newpa % 1000000007

print (ken + kenken + pa) % 1000000007