#include <stdio.h>
int main(void){
	int val = 0;
	scanf("%d",&val);
	
	int ans = 0;
	int count = 0;
	for(int i = 2;i < val;i++){
		for(int j = 2;j < i; j++){
			if(i % j == 0){
				count++;
			}
		}
		if(count == 0){
			ans += i;
		}else{
			count = 0;
		}
	}
	printf("%d",ans);
}