N = int(input())
M = 10**9 + 7
k0, k1, k2 = [0, 1, 0]
for _ in range(1, N):
    kk = (k1+k2) % M
    k2 = k1
    k1 = k0
    k0 = kk
print((k0+k1+k2)%M)