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