#include<stdio.h>
int main()
{
    int lb;
    int ub;
    int sum;
    scanf("%d %d", &lb,&ub);
    if(lb<=0 || ub<=0|| il>=ub)
    {
        printf("Invalid input");
    }
    else
    {
        for(int age=il; age<=ub; age++)
        {
            if (age%7==0)
               sum+=age;
        }
        printf("%d",sum);
    return 0;
}