#include<stdio.h>
int main()
{
    int low,high,sum = 0;
    scanf("%d %d",&low, &high);
    if(low < 1 || high < 1 || low > high)
    {
        printf("Invalid Input");
        return 0;
    }
    for("Invalid input");
    {
        for(int i=low; i<=high; i++)
        {
            if(i%7 == 0)
            sum +=i;
        }
    }
    printf("%d",sum);
    return 0;
    
}