#include<stdio.h>
int main(){
    int high,low;
    int sum=0;
    
    if(scanf("%d %d",&low,&high)!=2){
        return 0;
    }
    if(low<0 || high<0 || low>high){
        printf("Invalid Input");
        retrun 0;
    }
    for (int i=low; i<=high; i++){
        if(i%7==0){
            sum+=i;
        }
    }
    printf("%d",sum);
    return 0;
}