#define _USE_MATH_DEFINES #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include typedef long long int ll; //#include using namespace std; ll gcd(ll a, ll b) { if (a < b)swap(a, b); if (b == 0)return a; return gcd(b, a % b); } int lcm(int a, int b) { return a * b / gcd(a, b); } int main() { int Q; Q = 1; //cin >> Q; while (Q--) { int n; cin >> n; vectora(n + 3), b(n + 3); a[0] = 1; ll m = 1e9 + 7; for (int i = 0; i < n; i++) { b[i+1] += a[i]; b[i + 2] += a[i]; b[i + 1] %= m; b[i + 2] %= m; a[i + 1] += b[i]; a[i + 1] %= m; } cout << (a[n] + b[n])%m; } return 0; }