#include <stdio.h>
long long sum(long long n){return n*(n+1)/2;}
int main(){
  int n;
  scanf("%d",&n);
  long long ans;
  ans=sum(n)-sum(n/3)*3-sum(n/5)*5+sum(n/15)*15;
  printf("%lld\n",ans);
  return 0;
}
