#include <iostream>
using namespace std;
typedef long long ll;
int main(void){
    // Your code here!
    int n;
    cin >> n;
    ll sum = 0;
    for(int i = 0; i < n; i++){
        if(i % 3 != 0 && i % 5 != 0){
            sum += i;
        }
    }
    cout << sum << endl;
    return 0;
}
