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