#include <algorithm>
#include <cmath>
#include <cstring>
#include <deque>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <string>
#include <unordered_map>
#include <vector>

using namespace std;
using ll = long long;

const ll MOD = 1e9 + 7;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int N;
    cin >> N;

    ll prev[3] = {};
    ll cur[3] = {};

    prev[0] = 1;

    for (int i = 0; i < N; i++) {
        cur[0] = prev[1] + prev[2];
        cur[1] = prev[0];
        cur[2] = prev[1];
        prev[0] = cur[0] % MOD;
        prev[1] = cur[1] % MOD;
        prev[2] = cur[2] % MOD;
    }

    cout << ((cur[0] + cur[1] + cur[2]) % MOD) << endl;

    return 0;
}