#include <stdio.h>
int main(){
    int lower , upper , sum =0, age;
    if (scanf("%d %d", &lower , &upper) ! = 2 ) {
        return 0;
    }
    if ( lower < 0 || upper < 0 || lower > upper) {
        printf( " invalid input \n");
    } else {
        for (age = lower; age <= upper; age++){
            if ( age % 7 == 0){
                sum += age;
            }
        }
        printf("%d\n", sum);
    }
    return 0;
    }