#include<iostream>
using namespace std;

int main(){
    int dp[5][4001] = {};
    for(int i = 0; i <= 1000; i++)  dp[1][i] = 1;
    for(int i = 1; i < 3; i++){
        for(int j = 0; j <= 1000*i; j++){
            for(int k = 0; k <= 1000*i; k++){
                dp[i*2][j+k] += dp[i][j]*dp[i][k];
            }
        }
    }

    int n;
    while(cin >> n) cout << dp[4][n] << endl;
    
    return 0;
}
