#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  while (cin >> n) {
    int sum = 0;
    for (int i = 0; i <= (n, 1000); i++) {
      for (int j = 0; j <= min(n, 1000); j++) {
        if (i + j <= min(n, 2000)) {
          int k = n - i - j;
          k = min(k, 2000 - k);
          sum += k + 1;
        }
      }
    }
    cout << sum << endl;
  }
  return 0;
}
