#include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cassert>
 
using namespace std;
 
#define FOR(i,k,n) for(int i=(k); i<(int)(n); ++i)
#define REP(i,n) FOR(i,0,n)
#define FORIT(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
 
template<class T> void debug(T begin, T end){ for(T i = begin; i != end; ++i) cerr<<*i<<" "; cerr<<endl; }
inline bool valid(int x, int y, int W, int H){ return (x >= 0 && y >= 0 && x < W && y < H); }
 
typedef long long ll;
const int INF = 100000000;
const double EPS = 1e-8;
const int MOD = 1000000007;
int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};
 
int main(){
  const int N = 4001;
  const int M = 4;
  int dp[M + 1][N] = {};
  dp[0][0] = 1;
  for(int i = 0; i < M; i++){
    for(int j = 0; j < N; j++){
      for(int k = 0; j + k < N && k <= 1000; k++){
        dp[i + 1][j + k] += dp[i][j];
      }
    }
  }
  int n;
  while(cin >> n) cout << dp[M][n] << endl;
  return 0;
}
