#include "bits/stdc++.h"
using namespace std;
#define print(x) cout<<x<<endl;
#define rep(i,a,b) for(int i=a;i<b;i++)
#define REP(i,a) for(int i=0;i<a;i++)
typedef long long ll;
typedef pair<int, int> PI;
typedef pair<int, PI> V;
typedef vector<int> VE;
const ll mod = 1000000007;

int main() {
  int n;
  cin>>n;
  int a=1,b=0,c=0;
  int ta,tb,tc;
  while(n--){
    ta=a,tb=b,tc=c;
    a=(tb+tc)%mod;
    b=ta;
    c=tb;
  }
  print(((a+b)%mod+c)%mod);
}