#include #define LL long long #define VI vector #define VVI vector> #define VVVI vector>> #define VB vector #define VL vector #define FOR(i,a,b) for(int i= (a); i<((int)b); ++i) #define RFOR(i,a) for(int i=(a); i >= 0; --i) #define FOE(i,a) for(auto i : a) #define ALL(c) (c).begin(), (c).end() #define RALL(c) (c).rbegin(), (c).rend() #define DUMP(x) cerr << #x << " = " << (x) << endl; #define SUM(x) std::accumulate(ALL(x), 0LL) #define MIN(v) *std::min_element(v.begin(), v.end()) #define MAX(v) *std::max_element(v.begin(), v.end()) #define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end()) #define BIT(n) (1LL<<(n)) #define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end()); #define EPS 1e-14 const std::string YES = "YES"; const std::string Yes = "Yes"; const std::string NO = "NO"; const std::string No = "No"; bool inside(int y, int x, int H, int W) { return 0 <= y && y < H && 0 <= x && x < W; } // 4近傍(右, 下, 左, 上) const std::vector dy = { 0, -1, 0, 1 }; const std::vector dx = { 1, 0, -1, 0 }; using namespace std; const LL MOD = 1000000007; int main() { cin.tie(0); ios::sync_with_stdio(false); int N; cin >> N; // dp[i]][j] = マスiでケンをj回だした vector> dp(N + 5, vector(3, 0)); dp[1][1] = 1; FOR(i, 0, N + 1) { FOR(j, 0, dp[0].size()) { if (j == 0) { // ケン (dp[i + 1][1] += dp[i][0]) %= MOD; } else if (j == 1) { // ケン (dp[i + 1][2] += dp[i][1]) %= MOD; // パー (dp[i + 1][0] += dp[i][1]) %= MOD; } else if (j == 2) { // パー (dp[i + 1][0] += dp[i][2]) %= MOD; } } } LL ans = 0; FOR(j, 0, 3) { (ans += dp[N][j]) %= MOD; } cout << ans << endl; return 0; }