mod = 10**9 + 7
n = int(input())

if n == 0:
    print(0)
    exit()

# Initialize dp and sum_prev arrays
dp = [[0, 0, 0] for _ in range(n + 1)]
sum_prev = [0] * (n + 1)

for i in range(1, n + 1):
    for j_idx in range(3):
        j_val = j_idx + 1
        if j_val > i:
            dp[i][j_idx] = 0
            continue
        prev_i = i - j_val
        if prev_i >= 0:
            total_prev = sum_prev[prev_i]
            current_j_val = dp[prev_i][j_idx]
            sum_val = (total_prev - current_j_val) % mod
        else:
            sum_val = 0
        if prev_i == 0:
            sum_val = (sum_val + 1) % mod
        dp[i][j_idx] = sum_val
    sum_prev[i] = (dp[i][0] + dp[i][1] + dp[i][2]) % mod

print(sum_prev[n] % mod)