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