using System;

class test1
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        int a = 1;
        int b = 2;
        int c = 3;
        int bp = (n == 1) ? a : b;
        const int r = 1000000007;

        for (int i = 3; i < n; i++)
        {
            bp = (b + c > r) ? (b + c) % r : (b + c);
            c = b;
            b = a;
            a = bp;
        }
        Console.WriteLine(bp);
    }
}