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