#include<iostream>
using namespace std;
int x[4500], n;
int main() {
	for (int i = 0; i <= 1000; i++) {
		for (int j = 0; j <= 1000; j++) {
			for (int k = 0; k <= 1000; k++) {
				x[i + j + k] += k;
			}
			for (int k = 1001; k <= 2000; k++) {
				x[i + j + k] += (2000 - k);
			}
		}
	}
	while (cin >> n) {
		cout << x[n] << endl;
	}
}