from sys import stdin, stdout, stderr

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

    N = int(input())

    k = [1, 0, 0]

    for i in range(N):
        k[0], k[1], k[2] = (k[1] + k[2]) % mod, k[0], k[1]

    ans = sum(k) % mod
    print(ans)

if __name__ == '__main__':
    solve()