N = int(input())
MOD = 10**9 + 7
dp = [[0]*4 for _ in range(N+10)]
dp[0][0] = 1
for i in range(N):
    for j in range(1, 4):
        dp[i+j][j] += sum(dp[i]) - dp[i][j]
        dp[i+j][j] %= MOD
        
ans = sum(dp[N]) % MOD
print(ans)