#include<iostream>
#include<algorithm>
using namespace std;

int main()
{
	int n;cin>>n;
	long long int dp[3][1000001]={};
	dp[0][0]=1;
	const int M=1e9+7;
	for(int i=1;i<=n;i++)
	{
		dp[0][i]=(dp[1][i-1]+dp[2][i-1])%M;
		dp[1][i]=dp[0][i-1]%M;
		dp[2][i]=dp[1][i-1]%M;
	}
	long long int ans=0;
	for(int i=0;i<3;i++)ans=(ans+dp[i][n])%M;
	cout<<ans<<endl;
	return 0;
}