// editor3
#include<stdio.h>
int main()
{
    int x,y;
    if(scanf("%d %d",&x,&y)!=2)
   {
       return 1;
   }
   if(x < 0||y < 0||x>y)
   {
       printf("Invalid input");
   }
   else
{
    int sum=0;
    for(int age=x;age<=y;age++)
    {
        if(age%7==0)
        {
            sum+=age
        }
    }
    printf("%d\n",sum);
}
return 0;
}