#include<stdio.h>
int main()
{
    int num1,num2, sum;
    sum = 0;
    scanf("%d %d",&num1, &num2);
    if(num1 < 0 || num2 < 0 || num1 > num2)
    {
        printf("Invalid Input");
        return 0;
    }
    for(int i =num1;i = num2; i++)
    {
        if(i%7==0)
        {
            sum = sum + i;
        }
    }
    printf("%d",sum);
    return 0;
}