from sys import stdin, stdout, stderr

def solve():
    mod = 10**9 + 7

    N = int(input())

    pa, ken, ken2 = 1, 0, 0

    for i in range(N):
        pa, ken, ken2 = (ken + ken2) % mod, pa, ken

    ans = (pa + ken + ken2) % mod
    print(ans)

if __name__ == '__main__':
    solve()