#include <bits/stdc++.h>
using namespace std;

int main(void){
    int n; cin >> n;
    int64_t sum = 0;
    
    for(int i = 0; i < n; i++){
        if(i%3 == 0 || i%5 == 0){
        }else{
            sum += i;
        }
    }
    
    cout << sum << endl;
    
    
}