p = 10**9+7
N = int(input())
dp = [[0 for _ in range(3)] for _ in range(N+1)]
dp[1][0] = 1
for i in range(2,N+1):
    dp[i][0] = (dp[i-1][1]+dp[i-1][2])%p
    dp[i][1] = dp[i-1][0]
    dp[i][2] = dp[i-1][0]
print((dp[N][0]+dp[N][1]+dp[N][2])%p)