#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <complex>
#include <string>
#include <sstream>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <functional>
#include <iostream>
#include <map>
#include <set>
using namespace std;
typedef pair<int,int> P;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-9
#define INF 2000000000
#define sz(x) ((int)(x).size())
#define fi first
#define sec second
#define SORT(x) sort((x).begin(),(x).end())
#define all(x) (x).begin(),(x).end()
#define EQ(a,b) (abs((a)-(b))<EPS)
int main()
{
	int n;
	while(scanf("%d",&n)!=EOF)
	{
		int t=min(n,1000);
		int a,b;
		int ans=0;
		for(int a=0;a<=t;a++)
		{
			for(int b=0;b<=t;b++)
			{
				if(a+b>n)continue;
				ans+=min(n-a-b+1,1001);
			}
		}
		cout << ans << endl;
	}
	return 0;
}