using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using System.Text;

public class Program
{

    public void Proc()
    {
        int stepCount = int.Parse(Reader.ReadLine());
        for (int i = 1; i <= stepCount; i++) {
            GetAns(0, i);
        }
        long ans = GetAns(0, stepCount);
        Console.WriteLine(ans);

    
    }

    private long Mod = 1000000000 + 7;

    private Dictionary<int, Dictionary<int, long>> dic = new Dictionary<int, Dictionary<int, long>>();
    private long GetAns(int prevStep, int remain) {
        if(remain == 0) {
            return 1;
        }
        if(remain < 0) {
            return 0;
        }
        if(!dic.ContainsKey(prevStep)) {
            dic.Add(prevStep, new Dictionary<int, long>());
        }
        if(dic[prevStep].ContainsKey(remain)) {
            return dic[prevStep][remain];
        }
        long ans = 0;
        for (int i = 1; i <= 3; i++) {
            if(i==prevStep) {
                continue;
            }
            ans += GetAns(i, remain - i);
            ans = ans % Mod;
        }
        dic[prevStep][remain] = ans;
        return ans;
    }






    public class Reader
	{
		private static StringReader sr;
		public static bool IsDebug = false;
		public static string ReadLine()
		{
			if (IsDebug)
			{
				if (sr == null)
				{
					sr = new StringReader(InputText.Trim());
				}
				return sr.ReadLine();
			}
			else
			{
				return Console.ReadLine();
			}
		}
		private static string InputText = @"



49993







";
	}

	public static void Main(string[] args)
	{
#if DEBUG
		Reader.IsDebug = true;
#endif
		Program prg = new Program();
		prg.Proc();
	}
}