#include<bits/stdc++.h>
using namespace std;
const int inr=1E9+7,l=1E7+3;
int a[l]={0,1,2,5};
int main(){
	int n;
	cin>>n;
	for(int i=4;i<=n;i++)a[i]=(2*a[i-1]% inr+a[i-3]% inr)% inr;
	cout<<a[n]<<'\n';
}

qaq(本地ok，洛谷ce)