#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<=uppert; i++)
    {
        if(i%7 == 0){
            sum += i;
        }        
}
printf("%d", sum);
return 0;
}