#include <bits/stdc++.h>
using namespace std;
int ab[2001];
int main() {
  int n;
  while (cin >> n) {
    int ans = 0;
    for (int i = 0; i < 2001; i++) ab[i] = 0;
    for (int a = 0; a <= 1000; a++)
      for (int b = 0; b <= 1000; b++) ab[a + b]++;
    for (int c = 0; c <= 1000; c++)
      for (int d = 0; d <= 1000; d++)
        if (n - c - d >= 0) ans += ab[n - c - d];
    cout << ans << endl;
  }
  return 0;
}
