#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, d, n, count[100], j;
  for (j = 0; j < 100; j++) {
    count[j] = 0;
  }
  j = 0;
  while (cin >> n) {
    if (n > 2000) {
      n = n - 2000;
      n = 2000 - n;
    }
    for (a = 0; a <= 1000; a++) {
      if (a > n) break;
      for (b = 0; b <= 1000; b++) {
        if (a + b > n) break;
        for (c = 0; c <= 1000; c++) {
          if (n - (a + b + c) > 1000 || n - (a + b + c) < 0)
            break;
          else {
            count[j] = count[j] + 1;
          }
        }
      }
    }
    cout << count[j] << endl;
    j++;
  }
}
