#define _USE_MATH_DEFINES #include <algorithm> #include <cstdio> #include <functional> #include <iostream> #include <cfloat> #include <climits> #include <cstdlib> #include <cstring> #include <cmath> #include <map> #include <queue> #include <set> #include <sstream> #include <stack> #include <string> #include <time.h> #include <vector> using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair<int, int> i_i; typedef pair<ll, int> ll_i; typedef pair<double, int> d_i; typedef pair<ll, ll> ll_ll; typedef pair<double, double> d_d; struct edge { int u, v; ll w; }; ll MOD = 1000000007; ll _MOD = 1000000009; double EPS = 1e-10; int main() { int N; cin >> N; vector<vector<int> > dp(N + 1, vector<int>(3)); dp[0][0] = 1; for (int i = 0; i < N; i++) for (int j = 0; j < 3; j++) { if (j) dp[i + 1][0] = (dp[i + 1][0] + dp[i][j]) % MOD; if (j + 1 < 3) dp[i + 1][j + 1] = (dp[i + 1][j + 1] + dp[i][j]) % MOD; } int sum = 0; for (int j = 0; j < 3; j++) sum = (sum + dp[N][j]) % MOD; cout << sum << endl; }