N = int(input())

if N == 1:
    print(1)
elif N == 2:
    print(2)
else:
    dp = [0]*N
    for i in range(1,N):
        if i == 1:
            dp[i] = 1
        elif i == 2:
            dp[i] = 1
        else:
            dp[i] = (dp[i-2]+dp[i-3])%(10**9+7)
    count = dp[N-1]+dp[N-2]+dp[N-3]
    print(count%(10**9+7))