mod = 10 ** 9 + 7


def main():
    n = int(input())

    if n == 1:
        return 2

    kk = 1
    kp = 1
    pk = 0
    for i in range(2, n):
        kk, pk, kp = pk, kp, (kk + pk) % mod
    return (kk + pk + kp) % mod


print(main())