N = int(input())
L1 = [1, 0, 0]
L2 = [0, 0, 0]
for k in range(N-1):
    L2[0] = L1[2] % 1000000007
    L2[1] = L1[0] % 1000000007
    L2[2] = (L1[0] + L1[1]) % 1000000007
    L1 = L2
    L2 = [0,0,0]

print(sum(L1)%1000000007)