#pragma warning disable IDE0011 using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Numerics; using static System.Math; using static Extentions; class IO { int idx; string[] line; public void R(char sep = ' ') { line = Console.ReadLine().Split(sep); idx = 0; } public string S => line[idx++]; public string[] Ss => line.Skip(idx++).ToArray(); public char C => char.Parse(line[idx++]); public char[] Cs => line.Skip(idx++).Select(char.Parse).ToArray(); public int I => int.Parse(line[idx++]); public int[] Is => line.Skip(idx++).Select(int.Parse).ToArray(); public long L => long.Parse(line[idx++]); public long[] Ls => line.Skip(idx++).Select(long.Parse).ToArray(); public double F => double.Parse(line[idx++]); public double[] Fs => line.Skip(idx++).Select(double.Parse).ToArray(); public decimal D => decimal.Parse(line[idx++]); public decimal[] Ds => line.Skip(idx++).Select(decimal.Parse).ToArray(); public BigInteger B => BigInteger.Parse(line[idx++]); public BigInteger[] Bs => line.Skip(idx++).Select(BigInteger.Parse).ToArray(); public void Write(params object[] xs) { Console.Write(xs.First()); foreach (var x in xs.Skip(1)) Console.Write(" " + x); Console.WriteLine(); } } static class Extentions { public static int Mod = 1000000007; } static class Program { static void Main() { Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false }); Solve(new IO()); Console.Out.Flush(); } static void Solve(IO io) { io.R(); var n = io.I; var dp1 = new int[4]; var dp2 = new int[4]; var dp3 = new int[4]; dp1[0] = 1; dp2[0] = 0; dp3[0] = 0; dp1[1] = 0; dp2[1] = 1; dp3[1] = 0; dp1[2] = 1; dp2[2] = 1; dp3[2] = 1; for (var i = 3; i < n; i++) { dp1[3] = (dp2[2] + dp3[2]) % Mod; dp2[3] = (dp1[1] + dp3[1]) % Mod; dp3[3] = (dp1[0] + dp2[0]) % Mod; for (var j = 0; j < 3; j++) { dp1[j] = dp1[j + 1]; dp2[j] = dp2[j + 1]; dp3[j] = dp3[j + 1]; } } io.Write((dp1[3] + dp2[3] + dp3[3]) % Mod); } }