#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  while (cin >> n) {
    long long sum = 0;
    for (int a = 0; a <= 1000; a++) {
      for (int b = 0; b <= 1000; b++) {
        if (n - a - b <= 2000) sum += 2000 - (n - a - b) + 1;
      }
    }
    cout << sum << endl;
  }
}
