#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i< (n); ++i)
#define repi(i, a, b) for (int i = (a); i < (b); ++i)
#define all(x) (x).begin(), (x).end()
#define fore(i, a) for(auto &i:a)
using ll = long long;
#define DEBUG(x) cerr << #x << ": "; for (auto _ : x) cerr << _ << " "; cerr << endl;
#include<atcoder/modint>
using namespace atcoder;
using mint = modint1000000007;
int main() {
	ll n; cin >> n;
	vector<vector<mint>> f(n+1, vector<mint>(3, 0));
	f[1][0] = 1;
	if(2 <= n)f[2][1] = 1;
	if(3 <= n)f[3][2] = 1;
	for(int i = 1;i < n;i++){
		rep(j, 3){
		  if(i+1 <= n && j != 0)f[i+1][0] += f[i][j];
			if(i+2 <= n && j != 1)f[i+2][1] += f[i][j];
			if(i+3 <= n && j != 2)f[i+3][2] += f[i][j];
		}
	}
	cout << (f[n][0]+f[n][1]+f[n][2]).val() << endl;

}