N = int(input())
MOD = 10 ** 9 + 7

# dp[i][x] := i番目が「ケン」「ケンケン」「パ」となるような通り数
dp = [[0, 0, 0] for i in range(N)]
dp[0][0] = 1
for i in range(1, N):
    dp[i][0] = dp[i - 1][2]
    dp[i][1] = dp[i - 1][0]
    dp[i][2] = (dp[i - 1][0] + dp[i - 1][1]) % MOD

print(sum(dp[-1]) % MOD)