#include<stdio.h>
int main()
{
    int l,h;
    scanf("%d %d",&l,&h);
    if(l<0 || h<0 || l>h)
    {
    printf("Invalid input");
    return 0;
    }
    int sum = 0
    for(int i=a;i<=b;i++)
    {
    if(i%7==0)
    {
     sum += i;
    }
    printf("%d\n",sum);
    return 0;
}