#include<iostream>
using namespace std;

int main(){
	int a=1,b=0,c=0,n,ta,tb,tc,p=1000000007;
	scanf("%d",&n);
	while(n--){
		ta=a;tb=b;tc=c;
		a=(tb+tc)%p;
		b=ta;
		c=tb;
	}
	printf("%d\n",((a+b)%p+c)%p);
	return 0;
}