#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(i=low;i<=high;i++)
    {
        if (1 % 7 == 0)
        sum += i;
    }
    printf("%d", sum);
    return 0;
}