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