#include <bits/stdc++.h>
using namespace std;

void solve(int n) {
	int cnt = 0;
	for (int i = 0; i <= 1000; i++) {
		for (int j = 0; j <= 1000; j++) {
			if (n - i - j >= 0) {
				if (n - i - j <= 1000) {
					cnt += n - i - j + 1;
				} else if (n - i - j <= 2000) {
					cnt += 2000 - (n - i - j) + 1;
				}
			}
		}
	}
	cout << cnt << endl;
}

int main() {
	int n;
	while (cin >> n) {
		solve(n);
	}
}
	