#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  int ans[4001] = {0};
  for (int i = 0; i <= 1000; i++) {
    ans[i] = 1;
  }
  for (int i = 1; i < 4; i++) {
    for (int j = 4000; j > 0; j--) {
      for (int k = 0; k < j; k++) {
        ans[j] += ans[k];
      }
    }
  }
  while (cin >> n) {
    cout << ans[n] << endl;
  }
}
