using System; using System.Collections.Generic; using System.Linq; class Program { static void Main(string[] args) { var N = sc.ReadInt(); var dp = new ModInt[N + 10, 3]; dp[0, 0] = 1; for (int i = 0; i < N; i++) { for (int j = 0; j < 3; j++) { // パ if (j > 0) { dp[i + 1, 0] += dp[i, j]; } // ケン if (j < 2) { dp[i + 1, j + 1] += dp[i, j]; } } } var ans = dp[N, 0] + dp[N, 1] + dp[N, 2]; Console.WriteLine(ans); } public struct ModInt { public const long Mod = (int)1e9 + 7; public long num; public ModInt(long n) { num = n; } public override string ToString() { return num.ToString(); } public static ModInt operator +(ModInt l, ModInt r) { l.num += r.num; if (l.num >= Mod) l.num -= Mod; return l; } public static ModInt operator -(ModInt l, ModInt r) { l.num -= r.num; if (l.num < 0) l.num += Mod; return l; } public static ModInt operator *(ModInt l, ModInt r) { return new ModInt(l.num * r.num % Mod); } public static ModInt operator /(ModInt l, ModInt r) { return l * Inverse(r); } public static implicit operator ModInt(long n) { n %= Mod; if (n < 0) n += Mod; return new ModInt(n); } public static ModInt Pow(ModInt v, long k) { return Pow(v.num, k); } public static ModInt Pow(long v, long k) { long ret = 1; for (k %= Mod - 1; k > 0; k >>= 1, v = v * v % Mod) if ((k & 1) == 1) ret = ret * v % Mod; return new ModInt(ret); } public static ModInt Inverse(ModInt v) { return Pow(v, Mod - 2); } private static List Facs = new List { 1 }; public static ModInt Fac(int n) { for (int i = Facs.Count; i <= n; i++) { Facs.Add(i * Facs[i - 1]); } return Facs[n]; } public static ModInt nCr(int n, int r) { if (n < r) return 0; if (n == r) return 1; //var b = new BinomialCoefficient(n); //return b[n, r]; return Fac(n) / (Fac(r) * Fac(n - r)); } } public class BinomialCoefficient { public ModInt[] fact, ifact; public BinomialCoefficient(int n) { fact = new ModInt[n + 1]; ifact = new ModInt[n + 1]; fact[0] = 1; for (int i = 1; i <= n; i++) fact[i] = fact[i - 1] * i; ifact[n] = ModInt.Inverse(fact[n]); for (int i = n - 1; i >= 0; i--) ifact[i] = ifact[i + 1] * (i + 1); ifact[0] = ifact[1]; } public ModInt this[int n, int r] { get { if (n < 0 || n >= fact.Length || r < 0 || r > n) return 0; return fact[n] * ifact[n - r] * ifact[r]; } } public ModInt RepeatedCombination(int n, int k) { if (k == 0) return 1; return this[n + k - 1, k]; } } static Scanner sc = new Scanner(); } class Scanner { string[] S = new string[0]; int Index = 0; char[] Separators = new char[] { ' ' }; public string Next() { if (this.Index < this.S.Length) return this.S[this.Index++]; var line = ""; while (line == "") line = Console.ReadLine(); this.S = line.Split(this.Separators, StringSplitOptions.RemoveEmptyEntries); if (this.S.Length == 0) return this.Next(); this.Index = 0; return this.S[this.Index++]; } public string ReadStr() { return this.Next(); } public char ReadChar() { return this.Next()[0]; } public int ReadInt() { return int.Parse(this.Next()); } public uint ReadUInt() { return uint.Parse(this.Next()); } public long ReadLong() { return long.Parse(this.Next()); } public double ReadDouble() { return double.Parse(this.Next()); } public Tuple ReadTup(int add = 0) { return Tuple.Create(this.ReadInt() + add, this.ReadInt() + add); } public Tuple ReadTupLong(int add = 0) { return Tuple.Create(this.ReadLong() + add, this.ReadLong() + add); } public Tuple ReadTup3(int add = 0) { return Tuple.Create(this.ReadInt() + add, this.ReadInt() + add, this.ReadInt() + add); } public Tuple ReadTup4(int add = 0) { return Tuple.Create(this.ReadInt() + add, this.ReadInt() + add, this.ReadInt() + add, this.ReadInt() + add); } public int[] ReadIntArray(int n) { var array = new int[n]; for (int i = 0; i < array.Length; i++) { array[i] = this.ReadInt(); } return array; } public long[] ReadLongArray(int n) { var array = new long[n]; for (int i = 0; i < array.Length; i++) { array[i] = this.ReadLong(); } return array; } public double[] ReadDoubleArray(int n) { var array = new double[n]; for (int i = 0; i < array.Length; i++) { array[i] = this.ReadDouble(); } return array; } public char[] ReadCharArray(int n) { var array = new char[n]; for (int i = 0; i < array.Length; i++) { array[i] = this.ReadChar(); } return array; } public string[] ReadStrArray(int n) { var array = new string[n]; for (int i = 0; i < array.Length; i++) { array[i] = this.ReadStr(); } return array; } public Tuple[] ReadTupLongArray(int n, int add = 0) { var array = new Tuple[n]; for (int i = 0; i < n; i++) { array[i] = this.ReadTupLong(add); } return array; } public Tuple[] ReadTupArray(int n, int add = 0) { var array = new Tuple[n]; for (int i = 0; i < n; i++) { array[i] = this.ReadTup(add); } return array; } public Tuple[] ReadTup3Array(int n, int add = 0) { var array = new Tuple[n]; for (int i = 0; i < n; i++) { array[i] = this.ReadTup3(add); } return array; } public Tuple[] ReadTup4Array(int n, int add = 0) { var array = new Tuple[n]; for (int i = 0; i < n; i++) { array[i] = this.ReadTup4(add); } return array; } }