#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

const ll mod = 1e9 + 7;
int n;
int dp[2][3];

int main() {
  cin >> n;

  int turn = 0;
  dp[turn][0] = 1;
  for (int i = 0; i < n - 1; i++) {
    dp[!turn][0] = dp[turn][2];
    dp[!turn][1] = dp[turn][0];
    dp[!turn][2] = (dp[turn][0] + dp[turn][1]) % mod;
    turn = !turn;
  }
  cout << (dp[turn][0] + dp[turn][1] + dp[turn][2]) % mod << endl;

  return 0;
}