/* ***********************************************
Author        :guanjun
Created Time  :2016/12/6 11:36:45
File Name     :hdu1284.cpp
************************************************ */
#include <bits/stdc++.h>
#define ull unsigned long long
#define ll long long
#define mod 90001
#define INF 0x3f3f3f3f
#define maxn 10010
#define cle(a) memset(a,0,sizeof(a))
const ull inf = 1LL << 61;
const double eps=1e-5;
using namespace std;
priority_queue<int,vector<int>,greater<int> >pq;
struct Node{
    int x,y;
};
struct cmp{
    bool operator()(Node a,Node b){
        if(a.x==b.x) return a.y> b.y;
        return a.x>b.x;
    }
};

bool cmp(int a,int b){
    return a>b;
}
int dp[40000];
int main()
{
    #ifndef ONLINE_JUDGE
    //freopen("in.txt","r",stdin);
    #endif
    //freopen("out.txt","w",stdout);
    int n;
    dp[0]=1;
    for(int i=1;i<=3;i++){
        for(int j=i;j<=36000;j++)
            dp[j]+=dp[j-i];
    }
    while(~scanf("%d",&n)){
        printf("%d\n",dp[n]);
    }
    return 0;
}