#include<stdio.h>
int main()
{
	int n, m;//从n到m的素数
	int i, x = 2;//i是素数判断,x是素数
	int count;//统计第几个素数了
	int sum = 0;//最后结果和
	
	scanf("%d %d", &n, &m);
 	for (count = 0; count <= 200;) {//题的范围
		int isPrime = 1;
		for (i = 2; i < x; i++) {
			if (x % i == 0) {
				isPrime = 0;
				break;
			}
		}
		if (isPrime == 1) {
			count++;
		}
		 if(count==n) {
			sum += x;
			n++;
		}
		x++;
		if (count == m) {
			break;
		}
	}
	printf("%d", sum);
	return 0;
}