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])