#ifndef LOCAL
#include <bits/stdc++.h>

using namespace std;

#define debug(...) (void(0))
#else
#include "algo/debug.h"
#endif

#include <atcoder/modint>
using mint = atcoder::modint1000000007;

void solve() {
    int N; cin >> N;
    mint a{}, b = 1, c{};
    for(int i = 1; i < N; i++) {
        mint nb = a, nc = b, na = b + c;
        a = na;
        b = nb;
        c = nc;
    }
    mint ans = a + b + c;
    cout << ans.val() << endl;
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int tt = 1;
    // std::cin >> tt;
    while (tt--) {
        solve();
    }
}