#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

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

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n;
  cin >> n;
  vector dp(n + 1, vector<mint>(3, 0));
  dp[0][0] = 1;
  rep(i, n) {
    dp[i + 1][0] = dp[i][1] + dp[i][2];
    dp[i + 1][1] = dp[i][0];
    dp[i + 1][2] = dp[i][1];
  }
  cout << (dp[n][0] + dp[n][1] + dp[n][2]).val() << '\n';
  return 0;
}