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