def main():
    MOD = 1000000007
    N = int(input())
    if N <= 2:
        print(N)
        exit()

    dp = [0] * (N + 1)
    dp[0] = 1
    dp[2] = 1
    for i in range(3, N + 1):
        dp[i] = (dp[i] + dp[i - 2] + dp[i - 3]) % MOD
    dp[N] = (dp[N] + dp[N - 1] + dp[N - 2]) % MOD
    print(dp[-1])

main()