N = int(input())

def solve(N):
    mod = 10**9 + 7
    if N < 3:
        return 1
    if N == 3:
        return 3
    N1 = [0] * (N + 1)
    N2 = [0] * (N + 1)
    N3 = [0] * (N + 1)
    N1[1] = 1
    N2[2] = 1
    N1[3] = 1
    N2[3] = 1
    N3[3] = 1
    for i in range(4, N + 1):
        N1[i] = (N2[i - 1] + N3[i - 1]) % mod
        N2[i] = (N1[i - 2] + N3[i - 2]) % mod
        N3[i] = (N1[i - 3] + N2[i - 3]) % mod
    return (N1[N] + N2[N] + N3[N]) % mod

print(solve(N))