knapsack

#include <iostream>
#include <vector>
using namespace std;

const int MX = 1e3 +50;

#define ll long long
const ll mod = 1e9 ;
ll dp[MX];
int n;


int main(){
    cin >> n;
    dp[0] = 1;
    for(int j = 1; j<n; j++){
        for(int i = n; i>=1; i--){
            if(i - j < 0) continue ;
            dp[i] += dp[i - j];
            if(dp[i] > mod) dp[i] -= mod;
        }
    }
    cout << dp[n] << "\n";

    return 0;
}